ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 43 



I. First of all, in regard to the kinetic phenomena of maturation, 

 he maintains that the primitive nucleus of the ovum is an ordinary 

 nucleus ; that it divides into eight batons (" troncons ") in two groups of 

 four; that there are always two polar bodies in A. megalocephala ; that 

 there are no globules, nor chromatic discs, nor prothyalosoma ; that the 

 typical kinetic figures are dimidial ; that the ypsiliform figure does not 

 exist as such. A new spindle of separation is formed, again a dimidial 

 figure, again no globules, discus, nor prothyalosoma. Each semi-spindle 

 bears at its equator two of the primitive batons. One of the groups is 

 isolated with the second polar body. The other remains in the ovum. 

 The two last batons form the final nucleus. The polar bodies owe their 

 formation to a true plasmodiaeresis, by the aid of a cellular plate. They 

 are true cells, and not nuclei. II. Variations of polar kinesis. The 

 author distinguishes three different types within the same genus Ascaris, 

 and maintains the great variability of the polar kinesis. III. The cellular 

 plate. In animals cell-division (plasniodiaaresis) is accomplished by 

 constriction, by aid of a cellular plate, or by both processes at once. 

 The cellular plate occurs in all kinds of cells. It occurs distinctly in 

 the formation of the polar bodies of Nematode ova. 



Polar Bodies in Ascaris.* — Prof. J. B. Carnoy adds several appendices 

 to his well-known, much-criticized, investigations on the phenomena of 

 maturation, fertilization, and division of Ascaris ova. He describes the 

 formation of polar bodies in A. clavata and A. lumbricoides, noting the 

 transversal equatorial division, the incomplete longitudinal division, its 

 possible retardation, the occasional absence of the polar ascent, the 

 normality of the polar kinesis, the diverse modes of separation to be 

 seen in one preparation. A second appendix is devoted to a discussion 

 of the normality of the figures. He emphasizes the fact of individual 

 variations. Some observations are made anent the critique of the 

 Hertwigs, and the method pursued by Boveri. A third appendix is for 

 the most part an answer to Flemming, and discusses the facts of varia- 

 tion in kinesis, maintaining the impossibility of any general formula. 

 In reply to Flemming's strictures on the new terminology, Carnoy 

 criticizes the old, and justifies his own. 



Fertilization of Ascaris megalocephala.f — Prof. 0. Zacharias has 

 made a fresh study of the process of fertilization in the case of Ascaris 

 niegalocephala, which has been honoured with the attention of so many 

 naturalists. He gives at the outset a short sketch of the well-known 

 series of researches on this subject, he notes the various points of con- 

 trast, for instance, between Nussbaum and Van Beneden, between Carnoy's 

 and Hertwig's theory, and so on, and expresses at the outset his con- 

 viction that what all observers from Auerbach onwards have regarded as 

 pronuclei are structures of entirely different import. 



I. Ova and Spermatozoa. — The author proceeds to describe the 

 reproductive elements themselves, noting the changes in the maturing 

 ova, the early hyaline spherules and cavities, the appearance of a mem- 

 brane, the peripheral position of the nucleolus and its various parts, the 

 subsequent division into two portions, the further division of each of 

 these into four, the differentiation of each of these into connected rows 



* La Cellule, iii. (1887) pp. 247-324. 



f Arch, f. Mikr. Auat., xxx. (1887) pp. 111-82 (3 pis.). For the author's method 

 sec infra, Microscopy p. 



