434 Fritsch and Rich. — Studies on the Occurrence and 
description (loc. cit.) were found. In some filaments zygospores were 
present in every cell, while in others cells containing zygospores alternated 
with vegetative cells (cf. Fig. io) ; in the latter case the zygospores had 
their long axes at right angles to the direction of the filament, and the 
cells containing them were abbreviated and deformed. The vegetative 
cells were slightly inflated on both sides (Fig. io) or only on one side 
(Fig. u), and had prominent pyrenoids in their chloroplasts. Other 
filaments of Spirogyra, present in the same sample (July 2, 1906) un- 
doubtedly belonged to .S. neglecta ; they were also in the reproductive 
Fig. 6. Spirogyra longata from Epsom. 
,, 7. „ ,, from Hendon. 
,, 8,9. S. neglecta forma from Abbot’s Pool. 
„ 10, 11. S. ternata from Sydenham 
Wells. 
condition. Earlier samples from the same pond contained abundant 
neglecta , but it was almost impossible to identify any of the Spirogyra 
Fig. 1. Spirogyra varians. From Tiltham’s 
Pond. 
„ 2, 3, 4. .S’. affinis. From Abbot’s Pool. 
,, 5. S. Weberi (Abbot’s), magnified 240 
times. 
as 6 1 . ternata . 
S. neglecta (Hass.), Kiitz., can thus exhibit considerable variation, and 
we met with another example of this in Abbot’s Pool. We were much 
puzzled in examining samples from this pond to find two Spirogyras of 
the same width, one of which was undoubtedly S. neglecta , while the other 
answered to no description we could find. It differed from S. neglecta 
in having rather broader chloroplasts with larger, better-marked pyrenoids, 
and in the absence of what Petit calls a 6 nervure centrale.’ Figs. 8 and 9 
