INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC, 49 



Absence of the Amnion in the Chick.* — M. Dareste draws 

 attention to the occasional absence of the amnion in the chick, ^ and 

 states that in some cases the embryo is, notwithstanding, quite 

 normally constituted, although it is possible that it would not have 

 lived to break the shell ; this is almost certain from the fact that the 

 absence of the amnion would, by hindering the complete development 

 of the allantois, produce asphyxiation of the embryo. Anomalies or 

 death are in such cases produced in various ways ; thus, the embryo 

 dies by " desiccation " if brought against the investing membrane of 

 the shell, and all goes to show that the function of the amnion is to 

 protect the embryo against the mechanical forces which tend to com- 

 press it. In an " anamniotic " embryo of five days M. Dareste was 

 able to observe very active contractions, which is an interesting point, 

 inasmuch as independent contractions of the embryo have not hitherto 

 been observed until the seventh day ; and the movements as observed 

 by von Baer and Vxilpian, have been attributed to the contractility of 

 the amnion, which is first displayed on the sixth day ; it is now 

 seen that the embryo itself becomes contractile before the amnion, 

 and it seems certain that the contractile elements are first developed 

 in the epideimic layer of the embryo and thence propagated to the epi- 

 dermic layer of the amnion, which is in structural connection with it. 



This mode of activity is entirely independent of nervous influence ; 

 and is greatly aftected by the temperature to which the animal is 

 exposed, being most obvious from 35^ to 40^ C, so that it comes to be 

 comparable to the contractile activity of the chick's heart, a very 

 well known phenomenon, fii'st observed by Harvey. 



Development of Parrots. ] — Max Braun calls attention to a point 

 in the development of the spinal cord of Melopsittacus undulatus ; in 

 examining an embryo, which was at a stage corresj)Ouding to that of 

 the third day in the chick, he observed, in front of the posterior 

 extremity of the medulla, a small cleft in the medullary canal which 

 opened into the endoderm, and so put into communication the rudi- 

 mentary intestine and the medullary canal. Treated with a weak 

 solution of chromic acid, this was rendered much more distinct ; 

 making transverse sections, and numbering them from behind 

 forwards, he found that, in section 44, the medulla was completely 

 closed ; in section 39 the medullary canal opened into the endoderm, 

 and remained open for one-fifth of a millimetre. After this the endo- 

 derm was closed up. The cleft was found in some later stages, but 

 gradually disappeared. The author has souglit for signs of it in the 

 chick, but in vain ; he thinks, however, that he has been able to discern 

 it in the pigeon, and Gasser has lately noticed its presence in the 

 goose. Professor Eauber has given the name of blastostoma to this 

 curious clcft.J 



Development of the Ova of Salamandra maculosa and Anguis 

 fragilis. § — Dr. Born, of Breslau, communicates a somewhat frag- 

 mentary but very interesting note on an attempt to dcveloi) the oval 



* ' Coniptcs Rendus,' Ixxxviii. (1879) p. 1329. 

 t 'Rev. Intornat. Sci.,' ii. (1879) p. 359. 

 X ' Zool. Anzciger,' ii. (1879) p. 502. § Ibi.l., j). 580. 



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