ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
379 
that the regular arrangement of the chromatin may render the retina 
more permeable by light, which may be of advantage to nocturnal 
animals. 
c. General. 
Development of Blood-corpuscles.* — Dr. C. S. Engel has made a 
detailed study of the development of the blood during the first half of 
embryonic life in the pig, and prefixes to his paper a list of the various 
kinds of red blood-corpuscles as recognised by him, together with a 
description of their staining reactions. The list includes the follow- 
ing seven forms : — (1) Ordinary non-nucleated red blood-corpuscles, 
which become red when treated with a mixture of eosin and methylen- 
blue and orange in Ehrlich’s triacid ; they are therefore ortliochromatic. 
(2) Normoblasts, which are also orthochromatic, but differ from 1 in the 
presence of a small nucleus. They occur in embryonic life and in 
anaemia. (3) Toly chromatic normoblasts which become violet in eosin 
and methylen-blue and red in triacid. They have r a much larger 
nucleus than 2, and are always present when the orthochromatic normo- 
blasts are present. (4) Polychromatic megaloblasts similar to 3, but 
with an even larger nucleus ; they are not very sharply marked off from 3. 
(5) Metrocytes, large nucleated cells found only in the earliest embry- 
onic stages. They are divided into two generations, according to their 
staining reactions and the condition of the nuclei, and are the direct fore • 
runners of 1. (6) Orthochromatic macrocytes which are without nuclei 
and appear late in embryonic life and in anaemia. (7) Polychromatic 
erythrocytes which vary in s ; ze between 6 and 1. The author then 
proceeds to describe the blood of different regions of the body in the 
successive stages of the embryo pig, and the relative number of these 
elements present in the different stages. 
Development of Spermatozoa.f— Prof. Earl Grobben publishes a 
short paj>er on the arrangement of the developing sperms in bundles 
which has been observed in the testes of many different animals, and on 
the relation of the sperms to the “ nutritive ” cells of the testes. Both in 
Vertebrates and in Mollusca the sperm bundles are arranged with the 
heads pointing outwards and the tails towards the lumen of the organ. 
The heads of the sperms are in intimate connection with the substance 
of the nutritive cells, and in each bundle point towards the nucleus of 
the nutritive cells. The author believes that these cells are undoubtedly 
nutritive, and that the heads of the sperms are attracted towards their 
nuclei because here the metabolic processes are most rapid. The 
arrangement in bundles is explained by the supposition that the nuclei 
of the sperms exercise upon one another an attraction similar to that 
which the nucleus of the nutritive cell exercises upon them, and also by 
the original position of the sperm-producing cells (spermatids). Prof. 
Grobben is doubtful whether there is any intimate connection between 
the cytoplasm of the sperms and of the nutritive cell, and believes that 
the relation is similar to that existing between intracellular parasites, 
such as Eimeria, and the cells which they infest. 
* Arch. Mikr. Anat., liv. (1899) pp. 24-59 (1 pi.). 
f Zool. Anzeig., xxii. (1899) pp. 101-8. 
