436 Scientific Intelligence. 
_ 8. Pterodactyl in the English Chalk.—Portions of the jaws with teeth, 
and of several characteristic bones of the extremities of a Pterodactyl, 
have recently been discovered in the chalk of Kent, England, in a lo 
cality that has furnished the large bones which have hitherto been taken 
for those of a bird as large as an Lona ke but which — me 
to a flying reptile. 
Ill. Zooxoey. 
1. On the Formation of Cells; by M. Coste, (Ann. Mag. Nat. Hist., 
xvii, p. 94, from Comptes Rendus, Dec. 22, 1845.)*—The most ap- 
propriate examples for supplying the necessary means for resolving the 
difficult problem of the formation of cells, should be found in those parts 
where the matter undergoes that primary elaboration which prepares 
the materials of the new individual. Hence the bases for its solution 
must be sought in the metamorphoses of the vite//us, and we there find 
the facts developed in so characteristic and evident a manner, that they 
may be verified by any one. But, before showing how it is that the 
amorphous matter assumes the cellular form, there is another condition 
of that matter, the history of which I shall rapidly trace, and with which 
it is not less important to be acquainted. I allude to that progressive 
subdivision by means of which it is employed for the production of or+ 
ganic spheres, which must be considered hereafter as special elements 
of the living tissues. We shall proceed. then, first, to study the mode 
of generation of these spheres in the vitellus of Mammalia, subsequently 
tracing it wherever it occurs. When, in Mammalia, the seminal fluid 
has passed through the uterus and reached the Fallopian tubes so as to 
envelope the ovum with its moving molecules, in proportion as the 
molecules penetrate its substance, we see the yolk undergo the primary 
modifications which are about to induce the organization of the germ. 
It commences by becoming concentrated into a smaller volume, and 
forming itself into a granular globe so perfectly spherical and correctly 
outlined, that all the grains of which this globe is composed, and which 
are united together by means of a viscid diaphanous fluid, are apparently 
retained in the general form which their assemblage represents, by a 
delicate layer of the same fluid, which appears at the periphery as the 
representative of an enveloping membrane. But if, after having suffi- 
ciently guarded against optical illusions, we endeavor to develope the 
reality of the appearances which obscure it, we soon recognize that 
such a membrane does not exist, and that those observers, as for in- 
stance Barry, who have admitted its existence, have not pursued wan 
* This paper is a continuation of M. Coste’s researches, an account of which is 
given at p. 281 of the present volume.—Eds. Am. Jour. 
