282 Journal of Applied Microscopy. 



The author uses Hubrecht's terminology, but does not accept his conclusions 

 regarding the trophoblast. Assheton considers that early outer layer as hypo- 

 blastic in origin. The irregularity of the cleavage, the origin of the epiblast and 

 hypoblast and relations to the trophoblast, and the fate of the latter form the most 

 important points in this paper. a. m. c. 



Morpurgo, B. Uber die postembiyonale En- '^^^e author's investigations were car- 

 twicklung der quergestreiten muskeln von- ried on to determine the fundamental 

 weissen Ratten. Anat. Anz. 15, pp. 200-206. .. , ., , • i- ^1 



question whether muscles arise directly 



from fibers present at birth, or whether a new formation takes place. It has 

 recently been maintained that after birth the actual number of fibers decreases. 

 White rats were chosen for the studies and specimens were taken at given inter- 

 vals, newly born, fifteen days, one month old, and full grown ; care being taken to 

 have animals of the same family. The author finds that in the. first period of 

 growth, up to fifteen days, an actual increase in the number of fibers takes place ; 

 new structures rising by the mitotic division of generalized elements present in 

 the tissue. After the conclusion of these processes no further increase in the 

 number of fibers takes place, but with increasing length in the fibers the nuclei 

 multiply amitotically. The actual thickening of muscle fibres takes place inde- 

 pendently of increase in number of fibers or nuclei ; it has direct reference to the 

 amount of contractile substance. The three different steps are distinct in sig- 

 nificance. The first feature, number of fibers, is determined by the inheritance 

 and fundamental plan of the animal. The amitotic division, the second step, 

 accompanies an increase in the amount of substance in the preformed fibers and is 

 the result of normal activity of the muscle, and independent of heredity. Increase 

 of contractile substance depends least of all on inheritance and is caused by 

 nutrition and use ; as in cases of atrophy by inanition or active hypertrophy 

 from use. a. m. c. 



Dekhuyzen, M. C. Becherformige rote Blutkor- The author carried out a series of studies 

 perchen ("Chromokrateren"). Anat. Anz. on the blood COrpuscles of several ani- 

 , pp. .. _ -. mals, principally the brook lamprey, 



Petromyzon fluviatilis. He finds normally in the blood of this animal, which has, 

 as is well known, circular corpuscles, red cells of a becher-like form with two 

 poles, one rounded, convex, the opposite concave, pitted in. The eccen- 

 tric nucleus lies apparently adherent to the membrane of the convex pole. The 

 depression is sometimes so marked as to give a distinct invagination with a nar- 

 row mouth ; which may be slit-like, triangular, or many angled. These cells he 

 calls by a new name, " Chromokrateren," from analogy with Chromocyte and the 

 Greek for crater. After a series of observations on the Arthopod Thoxichilidium 

 and certain mammals, upheld by observations of other workers on Pantopods and 

 Capitellida^, the author concludes that the becher-like cell has the form of the 

 primitive blood cell, and hence its existence in certain primitive forms as Petro- 

 myzon, Pantopods, is most rational. A most interesting suggestion comes from 

 observations that these becher cells of Petromyzon were seen to extrude their 

 nuclei from the convex surface. Since many such shaped cells are found in the 

 blood-forming bone marrow of mammals, the author considers it probable that 



