xc GENERAL SUMMARY OF SCIENTIFIC AND 



Thus the germs of all animals (the amoeba and infusoria ex- 

 cepted) are alike, consisting of a sac composed of two layers 

 of cells. The theory he derives from this fact is stated under 

 the head of Zoology in this Record, 



Among the paj)ers of interest which have appeared during 

 the year on the embryology of the lower animals, is an article 

 by E. Kay Lankester in the Annals and Magazine of Natural 

 History^ being zoological observations made at Dohrn's Zoo- 

 logical Station at Naples. In this paper he shows that certain 

 mollusks originate the same as in the worms and vertebrates, 

 i. e., from two primitive layers of cells; and that, as shown by 

 Kowalevsky in other mollusks, there is an invagination or in- 

 pushing of these cells at one pole, just as in Amphioxus, the 

 lowest vertebrate. He also as^rees that the whole animal se- 

 ries above the Protozoa agree in possessing these two primi- 

 tive layers at one time of their development. 



The embryology of the spiders is discussed at length, with 

 many drawings in illustration, by M. Balbiani in ihQAiinales 

 des Sciences Natiirelles. 



An important paper on the embryology of the bony fishes, 

 from a study of the brook trout, is published by Dr. Oellacher 

 in Siebold & Kolliker's Journal of Scientific Zoology^ while 

 there are several short but important papers by F. M. Bal- 

 four, in the Quarterly Journal of Microscopical Science, on 

 the development of the layers of the blastoderm of the hen's 

 Qg^ an important contribution to the germ-layer theory ; 

 also an illustrated paper by the same author on tlie disap- 

 pearance of the primitive groove in the embryo chick, and a 

 very interesting illustrated paper on the develoj^ment of the 

 blood-vessels in the chick. 



Before turning to what has been done in systematic zo- 

 ology during the year, we may briefly notice the establish- 

 ment of biological institutions, which either aid zoologists 

 in developing our knowledge of structural and systematic 

 zoology, and of the geographical distribution of animals, or 

 which combine original research with educational advantages 

 of a hioh order. Such are the Zooloojical Station founded at 

 Naples by Dr. Anton Dohrn, the Anderson School of Natural 

 History at Penikese Island, in Buzzard's Bay, and the United 

 States Fish Commission, which has its head-quarters at dif- 

 ferent points along the coast of the Northern Atlantic States. 



