ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 49 



becomes replete with blood which cannot re-enter the circulation. The 

 psedogenesis M. Jaworowski refers to the rupture of the incompletely 

 developed ovarian membrane, and the liberation of ovules into the body- 

 cavity, where amid richly nutritive environment, they are able to develope 

 into larvEe without fertilization. 



II. The author next describes the development of the vascular system 

 in the chick, &c. His results differ considerably from those generally 

 accepted. The cells of the mesoderm are not distinctly separate, but bathed 

 in protoplasm. Some of them, instead of dividing and separating, form 

 multicellular endogenous vesicles. The protoplasm of the peripheral 

 layer collects at certain points and forms pseudopodia, which penetrate 

 among the other mesoderm cells. One of these processes becomes united 

 with that of an adjacent vesicle ; the others disappear. Meanwhile the 

 daughter-cells of the vesicle are being arranged, some peripherally in the 

 protoplasm, and others centrally. The former become elongated, flattened, 

 and connected to form the walls ; the latter form the blood elements. The 

 development of the heart is essentially similar. 



He sums up his conclusions as follows : — (1) That the membrane of 

 mesoderm cells is primitively formed of a network of ramified colls, 

 multiplying and elongating in all directions, and finally flattening out 

 to form an apparently homogeneous membrane ; (2) that the nucleus is a 

 daughter-cell, or rather a vesicle with walls composed of granulations bound 

 together by fundamental filaments; (3) that* the nucleolus is a vesicle, 

 and formed as a protoplasmic granule within another vesicle or develop- 

 ing cell, viz. the nucleus ; and (4) that the protoplasm of the cell is the 

 only formative and nutritive substance of these granules, which are in fact 

 cell-germs. The division of the nucleus is only apparent. All nuclei 

 arise as granules in the fundamental protoplasm. 



III. Blood in the adult organism. — M. Jaworowski finds the same way of 

 looking at cells and nuclei verified further in the blood of adult animals. 

 The serum is the creative and fundamental substance. In it are developed 

 the white corpuscles, which losing their nuclei and becoming granular 

 form mother-cells, of which the daughter-cells may either become red 

 blood-corpuscles or their mother-cells. The white corpuscles are mostly 

 formed in the lymphatic system, and the author does not distinguish them 

 from lymph cells. The mother-cells break up into daughter-cells especially 

 under the pressure of the capillary walls. Various other questions are 

 discussed. 



IV. Development of striped muscle. — M. Jaworowski has studied the 

 endogenous multiplication of cells in the developing striped muscles of 

 fish embryos (Alburnus). The least developed muscular mass consisted of 

 elongated cells surrounded by a membrane containing one or more daughter- 

 cells, some of which are already transformed into mother-cells of the 

 second order. He believes that an elongated primitive cell forms the 

 entire muscle, but it is difficult to give a brief elucidation of the process ; 

 nor is one much encouraged to attempt this till the close of the memoir 

 affords more definite information as to what M. Jaworowski means by the 

 words vesicle, cell, and nucleus. 



. Cilia.* — Herr J. Frenzel has studied the histology of cilia in a con- 

 siderable number of living forms, with the general result of demonstrating 

 their complicated structure. He gives a brief historical note of the 

 principal researches since Engelmann's classic memoir. 



In many instances Herr Frenzel observed that the " basal portions " 



* Arch. f. Mikr. Anat., xxviii. (1880) pp. .53-80 (1 pi.). 

 1887. E 



