Gronidia 



25 



of the Chamsesiphoniacege, but their occurrence in certain genera of the 

 Chroococcacese and the Hormogonese has only been demonstrated in 

 relatively recent times. Apart from the Chamaesiphoniacese, they have 

 been found in Qomphosphseria aponina, Chroococcus macrococcus, Anab&na 

 oscillarioides, Nostoc, Nostochopsis, Mastigocoleus, Leptochtvte, Plectonema, 

 Symploca, Lyngbya, Phormidium and Oscillatoria. 



In Chamtesiphon the gonidia arise by the formation of transverse walls 

 beginning at the distal end of the elongated cell. The cells thus cut off are 

 gonidia, which become rounded, and after they have burst through the 



D 



Fig. 16. A, colony of GomphospJi&ria aponina Ku'tz. with minute gonidia in the cells; x about 500 

 (after Schmidle). B, Xenococcus Schouxbiri Thur. attached to the rather wide gelatinous 

 sheath of Lyngbya semiplena J. Ag. ; x 1200. C, a few cells of an epiphytic colony of 

 Dermocarpa prasina (Reinsch) Born. & Thur., showing gonidia; x 800. D, three cells of 

 ChamKsiplwn gracilis Rabenh. ; x 500. E, part of filament of Phormidhnn autumnale (Ag.) 

 Gom. showing gonidia (g) and uiicrogonidia (m) ; x about 1000 (after Brand). 



delicate sheath at the distal extremity they are gradually set free. The 

 mother-cell may continue to grow, so that the gonidia are ultimately de- 

 veloped by abstriction from the free end of the protoplast 1 . In Godlewskia 

 the gonidia arise by both transverse and longitudinal divisions of the 

 protoplast of the mother-cell ; and in Pleurocapsa, Xenococcus, Hyella 

 and Dermocarpa the divisions are in three planes at right-angles or in 

 many intersecting planes. A similar kind of division also occurs during 

 the formation of gonidia in Gomphosphteria (Schmidle, '01). 



1 The cytology of this process still awaits investigation and should prove very interesting. 



