352 



Prof. Farmer, Messrs. Moore and Walker. [Nov. 17, 



which, in the case of animals, gives rise to the gametes immediately after 

 maiosis. But it is also now certain that there exist certain striking 

 similarities between the leucocytic and reproductive cells which are, in 

 themselves, highly suggestive, and this is not diminished by a consideration 

 of the earlier phylogenetic history of wandering and reproductive cells in 

 more primitive animals, for example, in sponges. 



For the present, however, and in the absence of more complete and accurate 

 knowledge on the evolution of the leucocytes, we may close by remarking 

 that the various peculiar characteristics of caucerous cells find their closest 

 analogies in the cytological processes that are exhibited in the formation of 

 the reproductive cells, and in those maiotic phenomena that so especially 

 distinguish them. 



DESCRIPTION OF PLATES. 

 Plate 8. 



Fig. 1. — Section of the growing edge of a young Carcinoma of the Rectum. 



\x, \y, \z. Enlarged parts of the same drawing. The letters c, d,e, correspond with 



those on the main figure. 

 a. The portion to the right represents the normal structure of the rectum ; b the zone 



in which transmutation from healthy to cancerous tissue is proceeding. 



c. Cell showing somatic division (see also 1 x). 



d. Cells in this zone containing leucocytes (see also 1 x and 1 y). 



e. Cell showing prophase of frrst maiotic (heterotype) mitosis (see also 1 z). 



f. Cut portion of crypts, but belong to the zone of transformation. 



g. Portions of the growth invading the adjacent layers. 



Plate 9. 



Fig. 2. — Section through young Epithelioma of the Penis. 



2x, 2y, 2 s. Enlarged parts of the same drawing. The letters a, b, c, d, correspond with 

 those of the main figure. 



a. Cells showing somatic (premaiotic) divisions. 



b. Cells showing somatic division, but with excessive number of chromosomes. 



c. Cell showing first maiotic (heterotype) division. 



d. Cell with leucocyte in its cytoplasm. 



Plate 10. 



Fig. 3. — Small Portion of the Testis of a Guinea-pig, showing (a) premaiotic cell dividing ; 



(b) cell in prophase of first maiotic (heterotype) division. In this it will be seen that 

 the centrosomes are at the centre of the archoplasm. 



Fig. 4. — Portion of the Testis of a Guinea-pig, showing (a) cells with the synaptic contrac- 

 tion, and the normal condition of the attraction sphere ; (b) late stage in the prophase 

 of the first maiotic division, showing the centrosomes detached from the archoplasm ; 



(c) homotype prophases showing. The same dismembered condition of the attraction 

 spheres. 



Fig. 5.— Cell from the early Cancer of the Rectum given in fig. 1, showing the somatic 



character of division. Compare with fig. 3, a. 

 Fig. 6. — Cell from Cancer of Rectum given in fig. 1, showing the characters of the 



prophase of the heterotype division. Compare with fig. 4, a. 



