DR. MARTIN BARRY’S RESEARCHES IN EMBRYOLOGY. 
553 
396. The remarkable process described in this memoir as giving origin to the new 
being in the mammiferous ovum (as already said), is no doubt universal. I think 
that there is evidence of its operation in the ova of Batrachian Reptiles, some osseous 
Fishes, and certain of the Mollusca-}-; though the explanations given of these have 
been of a very different character;};. 
Comparison of the Germs of Animals and Plants. 
39 7 - Schleiden’s description of the process by which the early changes in the 
vegetable germ (“ embryo”) are produced, is strikingly analogous in some respects to 
the one I have given of the incipient growth of the germ in the mammiferous ovum. 
This excellent observer, on the subject of the formation of cells in cells, states that 
the process “ presents itself in the embryonal extremity of the pollen-tube, that is, in 
a very much elongated cell.** # After the first cells, usually few in number, have formed, 
they rapidly distend so much as to fill the pollen-tube, and the latter soon becomes 
no longer visible as the old surrounding membrane. But immediately there arise in 
the interior of each of these cells several cytoblasts, which produce new cells, through 
the rapid distention of which the parent cells likewise cease to be visible and are ab- 
sorbed. The same process is repeated, and so on. But as the newly arisen cells have 
less and less space for distention, and hence become more and more minute, the pre- 
vious transparency ceases, through the constant generation of new cytoblasts taking 
place in the interior, and through the tissue becoming more and more compressed. 
From that period to the perfect completion of the embryo, the certainly logical 
inference leads us to the result, that the processes thus introduced continue the same, 
since no new force comes into action, which might determine us to admit a sudden 
change — more especially as we soon again meet with the same manifestation of vege- 
tative power §.” Schleiden then proceeds to show that the same process, by which 
the embryo arises, continues after the formation of the plant, and that cells never 
originate otherwise than in previously-formed cells. He says, in briefly summing up, 
“a simple cell — the pollen-tube — is its first foundation. In this arise cells; in them 
are developed other cells, and so on through life.” 
398. It will be seen that while it bears a general resemblance which is very stri- 
king, the description now quoted from Dr. Schleiden of the process to which the 
changes in the vegetable germ are referable, differs from that which I have given of 
Geschwiilste, I. Lief. Berlin, 1838 ; an excellent translation of which into English has been given by Dr. West.) 
I would refer particularly to the following figures of cells delineated by Professor Muller ; namely (West’s 
translation) Plate II. fig. 14. (Carcinoma Mammee simplex), — Plate III. fig. 2. (C. reticulare), — fig. 3 b . 
(C. alveolare), — fig. v. (Sarcoma of the Brain), — Plate IV. fig. 14. (Osteo-sarcoma), — Plate V. fig. 4. (Enchon- 
droma). 
f For instance, Planorbis cornea (Jacquemin, Nova Acta Acad. Cses. Leopold. Nat. Cur. 1838, p. 637.). 
1 The last explanation is that of Professor Bischoff, quoted in my “ Second Series” (par. 307. Note .)* 
§ L. c., pp. 162. 163. 
4 B 
MDCCCXL. 
