20 report— 1879. 



The primitive eggs are here, as elsewhere, true cells with nucleo- 

 lated nuclei, but without any boundary membrane. They are formed in 

 considerable numbers, but remain only for a short time separate and 

 distinct. After this they begin to exhibit amoeboid changes of shape, 

 project pseudopodial prolongations which coalesce with those of others in 

 their vicinity, and finally a multitude of these primitive ova become fused 

 together into a common plasmodium, in which, as in the simple egg cell 

 of other animals, the phenomena of development take place. 



In many of the lower plants a very similar coalescence is known to 

 take place between the protoplasmic bodies of separate cells, and con- 

 stitutes the phenomenon of conjugation. Spirogyra is a genus of Algae, 

 consisting of long green threads common in ponds. Every thread is 

 composed of a series of cylindrical cb ambers of transparent cellulose 

 placed end to end, each containing a sac of protoplasm with a large 

 quantity of cell-sap, and with a green band of chlorophyll wound spirally 

 on its walls. When the threads have attained their full growth they 

 approach one another in pairs, and lie in close proximity, parallel one to 

 the other. A communication is then established by means of short con- 

 necting tubes between the chambers of adjacent filaments, and across 

 the channel thus formed the whole of the protoplasm of one of the con- 

 jugating chambers passes into the cavity of the other, and then imme- 

 diately fuses with the protoplasm it finds there. The single mass thus 

 formed shapes itself into a solid oval body, known as a ' zygospore.' 

 This now frees itself from the filament, secretes over its naked surface 

 a new wall of cellulose, and, when placed in the conditions necessary for 

 its development, attaches itself by one end, and then, by repeated acts of 

 cell-division, grows into a many-celled filament like those in which it 

 originated. 



The formation of plasmodia, regarded as a coalescence and absolute 

 fusion into one another of separate naked masses of protoplasm, is a 

 phenomenon of great significance. It is highly probable that, notwith- 

 standing the complete loss of individuality in the combining elements, 

 such difference as may have been present in these will always find itself 

 expressed in the properties of the resulting plasmodia — a fact of great 

 importance in its bearing on the phenomena of inheritance. Recent 

 researches, indeed, render it almost certain that fertilisation, whether in 

 the animal or the vegetable kingdom, consists essentially in the coales- 

 cence and consequent loss of individuality of the protoplasmic contents 

 of two cells. 



In by far the greater number of plants the protoplasm of most of the 

 cells which are exposed to the sunlight undergoes a curious and important 

 differentiation, part of it becoming separated from the remainder in the 

 form usually of green granules, known as chlorophyll granules. The 

 chlorophyll granules thus consist of true protoplasm, their colour being 

 due to the presence of a green colouring matter, which may be extracted, 

 leaving behind the colourless protoplasmic base. 



