EMPLOYMENT OF CONSTRUCTIVE MATERIALS IN LOWER CRYPTOGAMS. 365 



In the lectures on physiological organography, I frequently mentioned the 

 remarkable fact that non-cellular plants, such as the Siphoneae among the Algae, 

 behave, so far as their external organisation and all biological matters connected 

 therewith are concerned, like ordinary cellular plants, and that the continually pro- 

 gressive cell-formation of the latter implies no essential difference whatever as opposed 

 to the processes of configuration of the non-cellular plants. This is confirmed anew 

 on seeing how, in Caulerpa for instance, the part of the non-cellular vesicle which 

 corresponds to the stem produces assimilating leaves containing chlorophyll, on the 

 one hand, and rhizoids on the under side, on the other ; and, so far as we are 

 informed concerning the assimilation and metabolism, and the movements and meta- 

 morphoses of material, and the relations between these and growth, essentially the 

 same processes take place in this non-cellular vesicle (which is nevertheless externally 

 and internally so sharply differentiated) as were found to occur in the most highly 

 developed plants with their microscopic cellular structure. Everything, of course, 

 becomes more and more simple the simpler the growth and mode of life generally 

 assumed by the Alga. 



