have not forgotten the poor; even the poorest in the place may have the use of it for their dead, by applying to a committee appointed for the purpose. I hope we shall all be preserved from quicklime burying, and from

.“ Gloomy aisles

Black-plaster'd, and hung round with shreds of 'scutcheons

And tatter'd coats of arms;"

and also from the rude hands of the grave-digger after our flesh is consumed; for it is anything but pleasant to see the remains of parents, brothers, sisters, and friends treated in a brutal manner by thoughtless mortals. If the plan were adopted which you have recommended, the air we breathe would become less tainted, and

"The sexton, hoary-headed chronicle,"

would be prevented from delivering grave lectures over the skulls of those he had buried. Peter Mackenzie. West Plean, June 7. 1843.

Cemeteries and Churchyards.— The taste, as well as a general feeling for improvements in our burial-grounds, is unquestionably on the increase; and, whatever internal discord there may be in churches, nobody seems disposed to quarrel with a plan for bettering and beautifying the churchyards. One step is wanting; viz. that it should become the fashion. Since you warmed me up upon the subject, I cannot tell you with what disgust I have looked upon the disgraceful condition of the churchyards I happen to have been in. Sunning Hill is one. There are the remains of very eminent men reposing there; Sir Home Popham, George Ellis, and General Fitzpatrick : and the place is overrun with rank dank weeds, suited to cover the remains of dead dogs, but most offensive when we think of the men whose last resting-places they dishonour; or, rather, the dishonour attaches to those who continue the practice of totally disregarding the state of our burial-grounds. Having often spoken upon the subject of late, I am glad to think that everybody acknowledges this; and, when a few examples have introduced the fashion, we may expect, I think, a general amelioration. In the mean time, I hope the national cemetery may not be lost sight of. There is a bill now before parliament, and which is extremely likely to pass, to facilitate the enclosure of waste lands. Such an act might very much facilitate the business of a company disposed to carry into execution your plan in the neighbourhood of Woking. The same machinery for effecting the enclosure of a parish thereabouts would give a company legal possession of the tract they might purchase of the parish as the ground of their operations. The bill itself promises great general benefit; and I hope, with all my heart, it may pass. With the aid of such men as you mention, Mr. Mackinnon and Mr. Hume, and I should add Sir John Easthope, if he would cooperate, it seems as if a company of the highest order would soon spring into existence, and produce something worthy to be deemed general and national.-H. A. M. June 12. 1843.

DIED suddenly, on the 6th of June, John Penn, Esq., of Lewisham, aged 72 years. Mr. Penn has been well known for many years as a civil engineer in very extensive business. Of late years he became much attached to gardening, and invented the mode of warming and ventilating which bears his name. He was a man of powerful intellect, liberal in his opinions, most kind and benevolent to his workmen, and universally respected and beloved.

Dropped down while walking in his nursery, and, a few minutes after he had returned to his house, died, on June 1., Mr. John Milne, Nurseryman, Stoke Newington.

THE

GARDENER'S MAGAZINE,

AUGUST, 1843.

ORIGINAL COMMUNICATIONS.

ART. I. Comparative Physiology. By R. LYMBURn.

(Continued from p. 352.)

IN Chap. III., On the Laws of Organic Developement, Dr. Carpenter remarks" that, though the labours of the naturalist and comparative anatomist have not yet established laws of the highest degree of generality, yet many subordinate principles have been based on a solid foundation, and many at first doubtful are daily receiving fresh confirmation. The most important part of the process of induction consists in seizing upon the probable connecting relation, by which we can extend what we observe in a few cases to all. In proportion to the justness of this assumption, and the correctness of our judgement in tracing and adopting it, will the induction be successful. The more extensive the acquaintance with nature, the more firmly is the belief impressed that some relation must subsist in all cases, however little we may be able to trace. It was formerly customary to regard similarity of external form and evident purpose as indicating the analogies between different parts, but the developement of the functions is often found to originate in Sources entirely different. The wings of birds, &c., are formed by expansions of the general integument over the anterior parts of the osseous system, while in insects they are formed by prolongations of the respiratory apparatus. In vegetables, the tendril is developed in the vine from the peduncle or flower-stalk; in the pea, from the petiole or leaf-stalk; in Gloriòsa, from the point of the leaf; and, in the singular genus Strophanthus, from the point of the petal. Function, therefore, is not dependent on developement, nor on structural analogy. There is little resemblance between the gills of a fish and the lungs of a quadruped, or the air tubes ramifying through the structure of an insect; and those who are in the habit of forming exclusive notions upon a hasty survey might be led to deny that any 3d Ser. 1843. VIII.

CC

real analogy could exist. The essential character of the function, however, is to bring the circulating fluid (blood or sap) into due relation with the atmosphere; and all that is needed is a membrane which shall be in contact with the air on one side, and the circulating fluid on the other. In all the forms of respiratory apparatus there is the same essential character, and their modifications are only to adapt them to the conditions of the structure at large. There is, functionally considered, a unity of composition, although not really analogous in structural character. În the vegetable kingdom, organs which correspond in structure, connexions, and developement, are observed to assume the most varied forms, and perform the most different functions.

"It has been maintained by some physiologists, that the same elementary parts exist in all animals, and the only difference between the various classes is in the respective developement of these parts. This is, however, true only in a restricted sense. In the Vertebrata, the skeleton of the fish may be shown to be composed of the same parts as that of a bird or quadruped, though the form of individual bones may be totally dissimilar; the lungs of the air-breathing Vertebrata exist in a rudimentary condition in fishes, some of the higher classes having the rudiments of a bronchial apparatus. Among the Articulata the same correspondence may be traced; but the classes of this division will not admit of being compared with those of Vertebràta. There are many plants which bear stamens only in one set of flowers, and pistils in another; and these may be caused to produce flowers entirely perfect, by supplying nourishment enough to develope the rudimentary organs. When any new function, or great modification of function, is to be performed, no entirely new structure is evolved for that purpose, the end being attained by a modification in some structure already present. In all the great divisions of organic beings, there is a fundamental correspondence amongst the different organs. Nature appears to have kept in view a certain definite type or standard, to which she has a decided tendency to conform, and departs from the original plan only to accommodate herself to certain specific and ulterior objects peculiar to particular races of created beings. This unity of composition, however, is sometimes interfered with, by the tendency of one division to approach to another, producing organs characteristic of an approximate division. The functional character of the organs furnishes a more general analogy than any we can trace from structure alone. The simplest plant differs from the most complex, principally, in that the whole surface participates in all the operations of absorption, exhalation, and respiration, which connect it with the external world; while, in the more complex

higher plants, those functions are confined to certain portions of the surface. The leaves and roots of the higher plants have a functional analogy with the simple membrane of the algæ, which absorbs and respires. Even in the highest animals, the organs adapted to those functions are essentially composed of a simple membrane, a prolongation of the external surface. The respiratory organs of plants are prolonged externally, like the gills of fishes: in terrestrial animals they are internal; the membrane of the tubes or cells exposing a large surface. The absorbing organs of plants are prolonged into the soil, while in animals they are distributed upon the walls of a cavity, fitted to prepare and retain the food. Still the same fundamental unity exists, and the spongioles in vascular plants, and the absorbent vessels in animals, have precisely the same essential character with the membrane which constitutes the general surface of the sea-weed and red snow. Throughout the whole animated creation, the essential character of the organs which all possess in common remains the same; whilst the mode in which that character is manifested varies with the general plan upon which the being is constructed.

In

"In the early stages of formation in organised beings of the higher classes, before the structure has been progressively developed, we may observe as great a dissimilarity to its ultimate condition, as exists between the lower and higher classes. the progress of developement we may trace a correspondence between the advance of the germ to maturity, and the ascent of the different races as they rise in their permanent condition in the scale of creation. The functions are more specialised, not so general; and there is a greater variety of dissimilar parts in the higher organisms than in the lower; the lower are more homogeneous, the higher more heterogeneous. A heterogeneous or special structure arises thus out of one more homogeneous or general, and this by a gradual change. When the different functions, however, are highly specialised, the general structure retains more or less the primitive homogeneity of function which originally characterised it. The doctrine of the correspondence between the transitory forms exhibited by the embryos of higher beings, and the permanent conditions of the lower, refers to individual organs alone, and not to the whole structure. higher animals and vegetables can never be mistaken for those of the lower classes, though the progress of individual organs from a general to a special type is discernible in the developement of the embryo, as well as in the ascending scale. Eccentric developement explains the malformations from arrestment of developement in the higher animals, causing monstrosity. The study of monstrosities in the vegetable kingdom has been peculiarly effectual in the elucidation of the laws regulat

The

ing the metamorphoses of organs, as the stamens or carpels reverting to the form of leaf, which may be regarded as the type of them all. In the labiate flowers the suppression of one stamen and the shortening of two others result merely from a deficiency in the evolution of rudiments, and not from alteration of structure; as is seen in the snapdragon having sometimes five stamens, and the petals all regularly spurred."

It is in the discovery of such general laws as those of developement noticed in this section, and of the functions in the following, that practice is greatly benefited by science. When we understand the methods in which the operations of nature are generally performed, we are often enabled to prevent adverse circumstances from being productive of so much harm, by retarding and preventing their effects; and, vice versâ, to promote and advance the action of those circumstances that are beneficial. When we can understand the different functions that the different parts of plants perform, and how and where these functions are developed, we shall have obtained a knowledge which, when joined to a proper understanding of the action of the stimulating agents formerly treated of, and of the way in which the food of plants assists in developement, will enable us to proceed on correct principles. Much no doubt remains to be done, but much has already been accomplished; and it is the duty of all practical cultivators to endeavour to understand that much. Did not science teach us, in its first rudiments, that the spongioles at the extremities of the roots were the true absorbent vessels, the manure might be applied to the stock of the root and become injurious rather than beneficial. As the absorbent vessels in animals are placed in contact with the alimentary canal, so do we find those of plants in contact with the soil, which acts as the stomach for the reception and preparation of their food. Liebig characterises the act of digestion in animals as being principally one of solution, the gastric juice (containing muriatic acid, and the substance similar to diastase, formed from the inner membrane of the stomach), with the oxygen of the saliva, and the heat and action of the stomach, reducing the food into a soluble state; in the same way as the action of the air, joined to the heat and moisture of the soil, reduces the substances deposited as food into a state fit for absorption. Digestion has been said to take place in the leaves; had this been the case, however, it would have reversed the normal order of developement, and the above remarks of Liebig restore the order of developement to its normal condition. Digestion being only a preparation for absorption, and not a chemical action, which he distinctly says it is not, prevents the necessity of reversing the order of developement, and placing digestion subsequent to, in place of before, absorption. The aeration of the circulating fluid