662 Lewis. — The Life History of Griffithsia Bornetiana. 
sporogenous lobe is by constriction, somewhat after the manner of the 
second method of cell-division described on page 650. The final result is 
the same in the two cases, i. e., the production of branched chains of 
carpospores. 
The sporogenous lobes of a single cystocarp are of various ages. 
Lobes with mature spores may be seen by the side of unicellular sporo- 
genous lobes, and usually all stages of development may be seen in a 
single cystocarp (Fig. 95). 
Each sporogenous lobe is covered with a gelatinous envelope, not 
easily seen until swollen with glycerine or a watery fluid. The individual 
spores seem to be without a cellulose wall, being enclosed only by the 
hautschicht. 
As a rule, all the spores of a single lobe become mature at the same 
time. The links of the chains break at the point where the callus-like 
plugs are developed, the connecting strands are drawn into the body of the 
spores, and the spores slip out of the gelatinous envelope and float away 
into the water. 
The number of spores produced in a cystocarp can hardly be estimated 
with certainty, because while the mature spores are being shed, new sporo- 
genous lobes are being inaugurated. From a study of several cystocarps of 
average size, it was found that about 6 lobes are present at one time, with 
an average of about 40 spores in each lobe, giving a total of about 240 
spores in a normal cystocarp. Undoubtedly the number of spores produced 
during the life of a cystocarp may often be greater than this. 
When set free, the spores present much the same appearance as the 
tetraspores described on page 670. They are oval in shape. Around the 
periphery is a zone containing rather dense cytoplasm and numerous 
flattened chromatophores, which sometimes present their edges, but usually 
their flat surfaces, to the outside. In the centre is the large nucleus, 
enveloped in a zone of homogeneous cytoplasm. The nucleolus, which 
contains the chromatin, is usually in the form of 12-14 rounded bodies in 
the centre of the nuclear cavity. The linin is scanty in amount, being 
barely visible around the periphery of the nucleus. Between the nucleus 
and the peripheral zone of chromatophores, the cytoplasm is very coarsely 
vacuolar (Fig. 96). 
In a few cases, spores have been noted which have germinated in situ , 
and which contain two nuclei. 
Nuclear divisions in the cystocarp are of the usual type. In the 
divisions of the sporogenous nuclei, the number of chromosomes is about 
fourteen (Fig. 97). 
Food material appears to be passed into the cystocarp from the 
vegetative cell on which it is borne. In the cytoplasmic pad occurs a great 
abundance of the spheres of food material mentioned on page 649, and it 
