BRIEFER ARTICLES 
CROSS-CONJUGATION IN SPIROGYRA WEBERI 
(WITH ONE FIGURE) 
The writer has reported* the occurrence of cross-conjugation in 
Spirogyra inflata (Vauch.) Rabh., which was found in material collected 
in April 1915. In the spring of 1917 another species was collected in 
cross-conjugation. Glycerine mounts were made and examined. The 
phenomenon in this case is very similar to that in S. inflata. Table I 
shows the dimensions of S. inflata and S. Weberi as given by WOLLE 
and DrTont, also the material collected by the writer in 1915 (which 
has been identified as S. imflata), and that collected in 1917 which 
corresponds sufficiently with S. Weberi to be identified with that species. 
TABLE I 
ZYGOTE ZYGOTE CELL VEGETATIVE CELL 
Length Width Length Width Length Width 
MR eas, 2xW 30-36 | Greatly inflated 42-144 | 14-18 
3015 COUT... 45 25.9 2 99-9 15.6 
S. Webeti.® 2 kc: 2xW a6 30 Sey inflated 100-350 | 18-25 
TIF COLT. 6 62.9 29.6 87.2 | Re: 
a Dimension according to WoLLE e and DeTont. 
{ Average of 15 measurements, 
Since there is a possibility of considerable variation in the size of a 
plant owing to various causes, such as food, light, heat, etc., it is probably 
well to add the fact of the great difference in the inflation of the zygote 
cells. WOLLE says that the zygote cell of S. inflata is greatly inflated, 
while S. Weberi is but slightly inflated. If we establish a ratio by 
dividing the diameter of the zygote cell (d) by the diameter of the vegeta- 
tive cell (d’), qr and apply it to the material collected in r915, we get 
d : 
iat 359 This 
* CUNNINGHAM, Bert, Sexuality of filament of Spirogyra. Bot. Gaz. 63:486- 
500. 1917. 
Botanical Gazette, vol. 66] [272 
d : : 
qe 22053 while applied to the 1917 material we get 
