. Lichens. Lichens. 56 CONSTITUENTS OF THE LICHEN THALLUS. Fig. 2 3. Cystococcus Cladon iae pyxidatae Chod. from cul- ture X 8oo (after Chodat). of species and he designates the algae, according to the lichen in which they occur, as Cystococcus Cladoniae pyxidatae, C. Cladoniae fimbriatae, etc. Meanwhile Paulson and Somerville Hastings^-by their careful research on the growing thallus have thrown considerable light on the identity of the Protococcaceous lichen gonidium. They selected such well-known lichens as Xanthoria parietina, Cladonia spp. and others, which they collected during the sprin
. Lichens. Lichens. 56 CONSTITUENTS OF THE LICHEN THALLUS. Fig. 2 3. Cystococcus Cladon iae pyxidatae Chod. from cul- ture X 8oo (after Chodat). of species and he designates the algae, according to the lichen in which they occur, as Cystococcus Cladoniae pyxidatae, C. Cladoniae fimbriatae, etc. Meanwhile Paulson and Somerville Hastings^-by their careful research on the growing thallus have thrown considerable light on the identity of the Protococcaceous lichen gonidium. They selected such well-known lichens as Xanthoria parietina, Cladonia spp. and others, which they collected during the spring months, February to April, the period of most active growth. Many of the gonidia, they found, were in a-stage of reproduction, that showed a simultaneous rounding off of the gonidium contents into globose bodies varying in number up to 32. Chodat had figured this method of "sporulation" in his cultures of the lichen goni- dium both in Chlorella Beij. and in Cystococcus Chod. (Fig. 23). It has now been abundantly proved that this form of increase is of frequent occurrence in the thallus itself Chlorella has been suggested as prob- ably the alga forming these gonidia and recently West has signified his acquiescence in this view^ Chlorella Beij. Occurring frequently on damp ground, bark of trees, etc., dividing into numerous daughter- cells, probably reduced zoogonidia (Fig. 23). Chodat distinguishes between Cystococcus and Chlorella in that Cystococcus may form zoospores (though rarely), Chlorella. only aplanospores. He found three gonidial species, Chlorella lichina in Cladonia rangiferina, Ch. viscosa and Ch. Cladoniae in other Cladonia spp. 3. COCCOBOTRYS Chod. The cells of this new algal genus are smaller than those of Cystococcus orProtococcus and have no pyrenoid. They were isolated by Chodat from the thallus of Verriicaria nigrescens (Fig. 24), and, as they have thick membranes, they adhere in a continuous layer or thallus. Chodat also claims to have isolated a
Size: 1651px × 1513px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, bookpublishercambr, bookyear1921
