222 
F. E. Fritsch. 
problems with reference to the heterocyst, which I do not feel 
prepared to dwell on here, but hope to return to at some future 
date. These cases are probably to be looked upon as abnormal, but 
that does not diminish their interest. 
The mature spores are not always elongated in the direction 
of the axis of the filament ; in some cases, though not very 
commonly, their long axis is placed more or less transversely or 
obliquely to that of the filament (cf. Figs. 17, 18 and 19). The ger¬ 
mination of such chains of spores often gives rise to complex 
appearances, such as that shown in Figs. 17 and 18. 
Borzi describes the germination of the spores in Anabaena in 
the following words 9 “ The first indication of germination is the 
appearance of a very delicate diaphragm in the interior of the 
spore, by means of which the contents appear to be divided into 
two cells. They are the initial elements of the new thread. 
Afterwards the membrane breaks on one side and the germ 
unfolds freely outside of the spore. Then the young thread 
appears, wrapped up in a thick layer of quite colourless mucilage.” 
Borzi does not figure these stages in Anabaena, but in his Figs 7-10 
on Plate X. the germination of spores of Sphaerozyga is shown. The 
lower drawing in fig. 7 represents a spore, whose contents have 
undergone division to form a filament of five cells (cf. my Figs. 9 and 
12), whilst in the upper figure one end of the filament is beginning 
to push its way out of the spore (coinparable to my Fig. 7). This 
type of germination belongs to the first of the two above described, 
but as 1 have already emphasised above in the material, I examined, 
division did not as a rule take place previous to the emission of the 
contents ; however this is a feature, which is likely to vary 
considerably and does not seem of much importance. Borzi either 
did not meet with the different types of gemination 1 have described, 
or overlooked them. 
The germination of the spores of Nostoc, which is unlikely to 
differ essentially from that of Anabaena, is shown on plates VII. 
and VIII. and here (Plate VII., fig 9, Plate VIII., Fig. 10) the 
spore-contents are not divided when first liberated. It may be 
well to quote Borzi’s description of the germination in this genus. 
The first indication of germination “ is the rupture of the 
membrane of the spore at some point of its surface. This is 
probably due to the sudden metamorphosis of the endospore into a 
1 Borzi. Note alia morfologia e biologia delle alghe Ficochromacec, 
Nuov, Giorn. Bot. Jtal. Vol 10. 1878. p. 261. 
