The London Botanical Society. 
over to the sporogenous condition. Of these the inner investment 
extends completely around the protoplast, whilst the outer one 
(the cell-sheath) envelopes the cell as a cylindrical sheath open at 
each end; the transverse septa are thus formed by the inner 
investment only, whilst laterally both envelopes of the cell can 
be distinguished. When a cell divides, the cell-sheath is split into 
two fresh sheaths by the development of a new intercellular 
septum ; each cell thus has an individual cell-sheath. As the spores 
mature they become widely separated from one another, whilst the 
cell-sheath closes in round the open ends, forming a complete 
exospore, the endospore being constituted by the inner investment. 
The cells of Gloeocapsa exhibit the same two envelopes, which here 
completely envelope the cell ; the cell-sheath is split during 
division, but the daughter-cells become widely separated by the 
excretion of intercellular mucilage, and the cell-sheath closes round 
and forms a complete investment (cf. mature spores of Anabaena). 
In Oscillaria the cell-sheath is no longer split during division, but 
forms a coherent whole round the filament; Lyngbyci only differs 
from Oscillaria in the presence of a consistent external mucilage- 
sheath. In the higher heterocystous forms (e.g. Tolypothrix and 
Rivularia) however the actual filament (within the external sheath) 
is provided with a cell-sheath, which is only in part coherent and 
shows a very marked moniliform structure. In young stages the 
inner investment is alone recognisable ; it is regarded as a modified 
plasmic membrane of a viscous, gelatinous nature, and it is possible 
that the intercellular protoplasmic connections of many observers 
are merely due to contractions, produced in the gelatinous 
transverse portion of the inner investment during staining. 
Professor Fujii of Tokio, Japan, exhibited preparations of the 
spermatozoids of Ginkgo biloba and gave some account of their 
normal and abnomal structure and of their behaviour in fertili¬ 
zation. He also described the germination of the pollen-grain in 
this Gymnosperm and criticised the retention of the terms “ stalk ” 
and “ body ” cell as wholly inappropriate. 
Professor F. W. Oliver exhibited a new seed from the Lower 
Coal-Measures recently received from Mr. J. Lomax. He stated 
that it was the smallest seed that, had come under his observation 
from this horizon, and whilst probably having affinity with the 
Lagenostoma-group it shewed certain interesting points of agree¬ 
ment with Gnctopsis elliptica as described by the late Monsieur B. 
Renault. 
