ZOOLOGY A.ND BOTANY, MICROSCOPY, ETC. 361 



method by "whicli it may be formed syntbetically. In tbe newt the 

 corresponding acid is contained in globules which have the micro- 

 scopic appearance of milk-globules, but differ from them chemically 

 by being soluble in water. The physiological properties of the 

 poison of the salamander are the same as those of that of the scorpion, 

 and resemble those which have been observed with amylcarbylamine. 

 The author has not yet studied the poison of serpents, but he thinks 

 that they have probably the same kind of constitution. The general 

 biochemical mode of formation may be thus defined. Every amide- 

 compound, whether simple or a peptone, may fix the elements of formic 

 acid in the nascent state, and give rise to a carbyl-compound of toxic 

 properties and unstable in composition. Every methyl group which 

 is insufficiently destroyed by oxidation gives rise not to carbonic but 

 to formic acid, and so furnishes the elements of the carbyl-compound. 



Development of Lacerta agilis.* — H. Strahl gives a further 

 account of the developmental process at the anterior end of the 

 embryo of Lacerta. In a previous communication by the same author 

 it had been pointed out that the head of the embryo consists up to a 

 comparatively late period of ectoderm and endoderm only, the meso- 

 derm being entirely absent. 



Some of the more important results of the present communi- 

 cation are as follows : — The vascular area which is at first only 

 developed at the sides of and behind the embryo grows forward 

 and unites above the head to form a single oval disk ; before this 

 has taken place the cleavage of the mesoderm is visible in the 

 anterior margins of the vascular area, and the fusion of the two 

 cavities thus formed leads to the imiting together of the two sides 

 of the vascular area. The larger anterior portion of the amnion is 

 formed by growth from before backwards without any lateral folding 

 of its ectodermic layer. The formation of the false amnion is very 

 diiferent from its formation in the cbick ; in the latter the folds of the 

 splanchnic layer of the mesoderm and of the endoderm appear before 

 the complete closure of the amnion, while in the embryo of Lacerta, 

 these same folds which inclose the embryo, and may therefore be 

 termed the false amnion, appear after the closure of the amnion. 

 Another difference between the embryo chick and the embryo lizard 

 is to be found in the relation between the closure of the body-cavity 

 and the closure of the head intestine ; in Lacerta the body-cavity 

 closes almost immediately after the closure of the intestine, while in 

 the chick the ventral sides of the body-cavity remain separate from 

 eacb other long after the closure of the intestine. The twisting of 

 the embryo on to the left side causes a like twisting of the anterior 

 portion of the amnion, which is by this time entirely closed ; at the 

 posterior end of the embryo, where the two folds of the amnion have 

 not yet become united, this twisting of the amnion does not take place, 

 inasmuch as the left fold grows more rapidly than the right, and so 

 the two, when they come to unite, remain in the same place as the 

 egg membrane, and do not participate in the twisting of the embryo. 



* Arch. f. Anat. u. Physiol. (Anat. Abtheil.), 18S4, pp. 41-88 (2 pis.). 



