SUMMARY OF CURRENT RESEARCHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(principally invertebrata and cryptogamia), 



MICROSCOPY. Etc.* 



ZOOLOGY. 



VERTEBRATA. 

 a. Embryology. + 



Blastocyst and Placenta of Beaver. :£ — Arthur Willey describes the 

 pre-placental blastocyst, the maternal trophospongia, the discoplacental 

 adhesion, and the established placenta. He calls attention to the signi- 

 ficance of the obplacental implantation with differentiation of erytb.ro- 

 cytophagous and leucocytophagous megalokaryocytes, and of the placental 

 keel. 



In one respect, the euplacental blastocyst of the beaver is the most 

 primitive known among existing Rodents, by reason of the persistence 

 of the umbilico-uterine connecting membrane, which is a consequence of 

 the periplacental implantation of the trophoblast. 



The keel extends from end to end of the elongated balloon-shaped 

 blastocyst, along its superior or mesometric side, dipping into the deep 

 placental groove. It probably represents an ancient or primitive 

 mechanism. It is argued that the exserted mesoblastic keel of the beaver 

 is comparable to the " Haftstiel " of Tarsius, monkeys, and man. 



Reproduction in Domestic Fowl.§ — M. R. Curtis gives an account 

 of a study of the occurrence of double and triple-yolked eggs and dis- 

 cusses the physiological bearing of the facts established. During six 

 years only three triple-yolked eggs were procured from more than three 

 thousand fowls. Each was laid by a different individual, and each was 

 the first egg of a young pullet. Twenty per cent of pullets beginning 

 to lay before they are seven months old lay among their first eggs one 

 or more with two volks, but in no bird has the laving; of double-volked 

 eggs been found to be " habitual." An eg^r with two or three yolks 



* The Society are not intended to be denoted by the editorial" we," and they 

 do not hold themselves responsible for the views of the authors of the papers 

 noted, nor for any claim to novelty or otherwise made by them. The object of 

 this part of the Journal is to present a summary of the papers as actually pub- 

 lished, and to describe and illustrate Instruments, Apparatus, etc., which are 

 either new or have not been previously described in this country. 



t This section includes not only papers relating to Embryology properly so 

 called, but also those dealing with Evolution, Development, Reproduction, and 

 allied subjects. 



+ Quart. Journ. Micr. Sci., lx. (1914) pp. 175-259 (8 pis. and 6 figs.). 



§ Biol. Bull., xxvi. (1914) pp. 55-83 (4 figs.). 



