494 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
These spores have the structure of the “primitive disc” which, during 
the early stages of growth of Orbitolites occupies the centre of the shells. 
When they are liberated each becomes the centre of a new disc. In 
Orbitolites , therefore, there is reproduction by spore formation. 
Depositions within Foraminifera.* — Dr. L. Rhumbler has studied 
these bodies, some of which Max Schultze, Carter, and others regarded 
as reproductive. (1) Within Truncatulina lobatula and others there is 
often a diatom allied to Cocconeis. (2) In Saccammina spliserica , 
Truncatulina lobatula , Hyperammina friabilis there are peculiar cor- 
puscles with a hyaline membrane. They may be faecal or possibly the 
results of decomposition. (3) A third kind of body is common in 
Foraminifera from muddy bottoms or from among rotting detritus, and 
also occurs in fallen-off spines of Ecbinocardium , &c. They are deposi- 
tions of silicate of iron and are the result of decomposition. 
Nuclear Division and Spore-formation in Rhizopods.f — Prof. A. 
Gruber has been able to detect karyokinetic division in Arcella. The 
stage observed was that showing two daughter asters. Noteworthy was 
the very large number of spindle-fibres. The number of chromatin 
loops was also great. Gruber has observed Arcellse with nineteen, and 
even thirty-two nuclei, thus confirming the occurrence of spore-formation. 
He also observed a specimen of Lecytliium hyalinum with eight nuclei. 
As a caution he notes how he discovered numerous small amoeboid 
organisms within Arcella ; they suggested spores ; but they were only 
parasites, for the two nuclei of the host were in some cases quite distinct. 
Dimorphism in Development of Hsematosporidia.j; — M. A. Labbe 
finds that Drepanidium ranarum and D. Danilevslcii have two modes of 
reproduction, as is shown by the essential differences in the spores, 
which may be called macrospores and microspores. Cytocysts with 
macrospores are of very variable size, and often develope in the leuco- 
cytes ; they are the only ones yet known, and agree with those already 
described by Pfeiffer. The cytocysts with microspores are found in the 
liver and spleen ; there may be here as many as fifty or sixty very small 
sporozoites, 3 to 5 /x long, elongated like bacteria, but provided with a 
nuclear spot. 
The cytocysts with macrospores are found both in spring and autumn, 
but it is only at the beginning of the summer that those with microspores 
are met with. 
* Nachr. K. Gesell. Wiss. Gotting., 1892, pp. 419-28. 
t Ber. Nat. Gesell. Freiburg i. B., vi. (1892) pp. 114-8 (1 pi.). 
X Comptes Bendus, cxvi. (1893) pp. 1209 and 10. 
