no NATURAL SCIENCE. Feb., 



he says in his memoir, " there can be little doubt that the conduction 

 of a stimulus, which can be readily observed in the leaves of Mimosa 

 pudica, is effected by this means." 



In the next year, 1883, observations had been brought so far 

 that both Gardiner (6) and, a little later, Professor Schaarschmidt (12) 

 were enabled to venture the opinion that continuity of the protoplasm 

 was not an exceptional phenomenon restricted to the comparatively 

 few cases noticed, but one which was universal in vegetable cells. 

 All subsequent facts tend to confirm and strengthen this view. 



The year 1883 was in every way an important one for the 

 establishment and extension of the doctrine ; the numerous publica- 

 tions which then appeared show that the idea had taken a firm hold 

 of the leading botanists of the day. Russow (8) had already 

 published a memoir on the subject, in which he expressed his belief 

 in the active part played by the connecting filaments in transmitting 

 dynamical stimuli. Professor Hillhouse (10) published a paper in 

 which he showed continuity to exist in the cells of the bases of many 

 leaves [Primus laurocerasus, ALsculus Hippo., Ilex, etc.). Schmitz (9) 

 issued his well-known work on the Florideae. Here also he could 

 demonstrate the existence of protoplasmic intercommunications. 

 Schmitz, however, was not quite the first to point out continuity in 

 the Florideae ; before him, Mr. Archer had noticed a connection 

 between the protoplasmic bodies of the cells of Ballia callitricha, and 

 Professor Percival Wright between those of Polysiphonia and Griffithsia 

 setacea. Both Messrs. Archer and Wright spoke of the continuity as 

 being direct through an open pore, and they also considered it to be 

 only a temporary connection which became broken at a later stage in 

 the history of the cell. Professor Schmitz and Gardiner are led to 

 believe that the continuity is both permanent and not direct but 

 indirect. That is to say, they think the continuity is effected not by 

 a single thick strand of protoplasm running through an open pit, but 

 by a number of delicate filaments traversing a porous membrane 

 (pit-closing membrane) which stretches across the pit or canal in the 

 cell-wall. It may be mentioned here that it is Gardiner's belief that 

 continuity is in all cases indirect, never direct. Mr. George Massee, 

 who has studied the subject in two species of Polysiphonia, thinks that 

 continuity is direct in the early stages, but that a sieve-like diaphragm 

 is subsequently developed across the pit. 



In a paper read before the Linnean Society in 1885 (16), Mr. Spencer 

 Moore gave an account of his work on continuity in some Florideae. 

 He also believes that the connection is direct in the young cells, but 

 that later it sometimes becomes indirect, while at other times it 

 remains direct throughout life. "The young cells," he says, "are 

 placed in communication by means of a fine filament, upon which is, 

 in most cases, placed a small nodule, just as a bead is strung upon a 

 thread." Both thread and nodule grow, the latter assuming the form 

 of a ring ; the protoplasm, encompassed by the nodule, gives rise to 



