284 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
point where the individuality of the organism is first attained, when it 
has acquired a something setting it down as the embryo of some par- 
ticular form, and — the wording is important — when it is first beginning 
to resemble its progenitors. It then bears no absolute likeness to them, 
but it is just beginning to look like them.” 
In the final part of his paper Beard argues that the mammary appa- 
ratus of Eutheria is, as compared with that of Metatheria, arrested in 
its development. 
Fertilisation in Ascaris.* — Prof. J. B. Carnoy replies to criticisms 
by the late von Erlanger and by Flemming, and argues in support of 
the conclusions which he has elsewhere f sought to establish along with 
his colleague H. Lebrun. 
The spermatozoon does not furnish either the alleged spheres or the 
central corpuscles seen before the first cleavage. These are part and 
parcel with the conjugated nuclei, and are the nucleoli. At the moment 
of segmentation they leave the nucleus and form the first kinesis. They 
only serve once, and are formed anew in the daughter-nuclei. Far 
from being permanent organs, the corpuscles are transitory structures 
associated with division. As to the spheres, they do not exist, except 
as transitory modifications of the ordinary cytoplasm. Carnoy protests 
against the theoretical prejudices which seem to him to be vitiating the 
observation of facts. 
Spermatogenesis in Mammals.J — Herr M. von Lenhossek has made 
a detailed investigation of spermatogenesis in mammals, especially in the 
rat. He lays most stress upon two conclusions : — (1) that the sperma- 
tozoon is to be regarded as an entire cell, as an element in which all 
the three characteristic components of the cell are to be found, viz. 
cytoplasm, centrosome, and nucleus ; and (2) that the second of these 
components, the centrosome, lies in the middle portion of the spermato- 
zoon in the form of Jensen’s terminal knob. 
Interstitial Substance of Testis. § — Herr Hans Beissner agrees 
with Herr Plato and others that the interstitial substance is constant 
in the functioning testis of the cat. But its distribution is not uniform 
throughout the organ, and its granular content varies considerably. It 
cannot be regarded as essential to spermatogenesis. 
Beissner did not find any preformed canals in the walls of the tubules, 
nor do the interstitial cells directly touch the membrana propria of the 
tubules. If there is an absorption of fat from the interstitial substance 
by Sertoli’s cells, it must be by means of fine pseudopodia from these 
cells. It is possible . that pseudopodia from Sertoli’s cells penetrate the 
walls of the tubules and come into relations with the fat. 
Behaviour of Reproductive Cells in Plants and Animals. || — Prof. 
Y. Heecker has made a detailed comparison of the phenomena of growth 
and maturation in the reproductive cells of plants and animals. The 
following common phenomena are emphasised; we use m. and f. as 
contractions for male and female. 
* La Cellule, xiv. (1898) pp. 7-25. 
t Verb. Anat. Ges., xi. Vers. (1897) pp. 65-9 ; La Cellule, xiii. (1897) pp. 63-195 
(2 pis.). X Arch. Mikr. Anat., li. (1898) pp. 215-318 (3 pis. and 1 fig.). 
§ Tom. cit., pp. 794-820 (1 pi.). 
|| Biol. Centralbl., xvii. (1897) pp. 689-705, 721-45 (about 40 figs.). 
