ZOOLOGY AND BOTANY, MICEOSOOPY, ETC. 47 



the primitive buccal cavity." The author would extend this conclusion 

 to other Tunicates, and criticizes the arguments of E. van Beneden and 

 Julin. The ciliated sac is most probably an olfactory organ, as many 

 authorities believe. Finally, the author has described the ganglion and 

 the distribution of the nerves. Transverse sections of the ganglion 

 exhibit two distinct layers : the outer composed of small rounded cells 

 pressed together, the inner consisting of finely granular and amorphous 

 substance. The nerves which spring from the ganglion are described in 

 three groups — superior or anterior, lateral, and inferior or posterior. 



Alternation of Generations in Salpa and Pyrosoma.* — Dr. L, Joliet 

 left among his xmpublished papers another contribution of interest. It 

 discusses the alternation of generations in species of Salpa and Pyrosoma. 

 The lamented author corroborated the observations of Kowalewsky and 

 defended the old theory of Chamisso — of a true alternation of generations 

 — against the objections of Brooks and Todaro. 



(1) The budding of Salpa is true budding, though complicated by 

 the fact that the already differentiated organs take part in it, each on its 

 own account. (2) The solitary form hitherto considered as asexual is 

 rightly so called. It does not contain an ovary nor a hermaphrodite 

 gland, but only the incipient rudiments of such a gland. (3) In the 

 alternation of generations, proceeding by blastogenesis, the asexual form 

 is produced sexually, and possesses a reproductive tissue, which may be 

 only potential and undifferentiated, or quite recognizable and already 

 differentiated. It is, however, unable to carry this on to complete 

 development, and entrusts it for this purpose to another form, or to 

 several successive forms produced by blastogenesis. Of these, the last 

 at least is sexual. This formula may be applied to Salpa, Pyrosoma, 

 other compound Ascidians, and to several hydroids. 



B. Bryozoa. 



Anatomy and Histology of Membranipora pilosa-f— Herr W. Freese 

 commences his account of this Polyzoon with a description of its 

 ectocyst, external appearances, and varieties, three of which are to be 

 distinguished. The endocyst of adult animals merely forms a thin 

 meshwork of protoplasmic filaments in which no cell-boundaries can be 

 distinguished ; in stained pieces the small masses of protoplasm are 

 seen to be almost completely formed by large, round, or smaller oval 

 nuclei with distinct nucleoli ; the surrounded protoplasm is very small 

 in quantity. The endocyst only exhibits a truly epithelial structure 

 at the point where it extends over the rosette-plates ; as in Flustra 

 memhranacea, there is an epithelium formed of cylindrical cells ; this 

 is unilaminate, and forms a lens-like stopper. 



The so-called perigastric cavity or space between the ecto- and 

 endocyst corresponds to the body-cavity of other animals ; the parietal 

 muscles, which are found in it, consist of from three to ten fibres in each 

 bundle ; the fibres are somewhat more delicate than those of the other 

 free muscles, and stain less deeply. The author agrees with most of 

 the recent histologists in refusing to ascribe, with F. Miiller, a nervous 

 nature to the funiculi laterales and funicular plate ; and he agrees rather 

 with Nitsche in thinking that the plate is an organ which serves to keep 



* Op. cit., pp. 97-102. t Arch. f. Naturgesch., xlv. (1888) pp. 1-72 (2 pis.). 



