Francis E. Lloj'd — 148 — Carnivorous Plants 



LoEW and Bokorny, so designated by them because of its imputed 

 peculiar properties which place it in a category of substances which 

 may be regarded as bridging the gap between the non-living and the 

 living parts of the cell. These peculiarities were recited by Erna 

 Janson, who, working in Loew's laboratory, examined aggregation 

 from the point of view thus indicated. Her paper (1920) cannot be 

 said to indicate a full apprehension of the observations of those workers 

 (Gardiner, de Vries, Akerman, especially the last two named) who 

 had described in much detail the curious and complicated happenings 

 which take place during aggregation in the Darwinian sense. Before 

 resuming Janson's work, it would profit us to look first at that of 

 Akerman, who while differing from de Vries in the interpretation of 

 certain details, nevertheless agrees with him about the general trend of 

 affairs. Akerman used pepsin as the stimulating substance which, 

 when applied to the gland, quickly causes movement responses and ag- 

 gregation. The course of events he described as follows: 



At first the peripheral protoplasm is thin, and displays rotation 

 (cyclosis). This movement, as threads and ultimately plates of proto- 

 plasm arise, becomes more comphcated, and changes into a true circu- 

 lation, becoming more and more active. Meanwhile the peripheral 

 layer of protoplasm thickens, even to twice the original thickness. 

 Folds of protoplasm, impinging on the vacuole, become strands which 

 become thicker and more and more extensive till they cut into the 

 vacuole and ultimately break it up into numerous small ones. The 

 change in volume of the protoplasm is accompanied by a reduction in 

 volume of the vacuoles, the substances in solution therein (the red pig- 

 ment, tannin, etc.) becoming more concentrated till the specific gravity 

 of the two are reversed, that of the sap increasing, as shown by cen- 

 trifuging. At length the vacuoles display remarkable activity. They 

 elongate, become vermiform and move, creeping about each other in a 

 most dramatic fashion. In my own experience it has been found diffi- 

 cult to make drawings of them as the movements, apparently slow, are 

 fast enough to defy adequate representation of the proceedings. Aker- 

 man affords a fair idea of the condition regarded for the moment as 

 static in his Fig. 3, but even this does not do the matter justice. But 

 the photographic reproduction of three exposures of a single cell two 

 and fifteen minutes apart and two two minutes apart, are truly 

 illuminating (77 — i). We may here recall de Vries' own figures, not 

 to be ignored. Such activity can be sustained for hours, even days. 

 At last a reversal of changes sets in and proceeds till at length the 

 primary condition is attained. During the forward progression 

 Schimper thought to have observed the formation of new vacuoles, 

 new evidently as they did not contain red pigment; de Vrees also. 

 These Akerman did not see. He also supports Gardiner, Schimper, 

 Goebel in his view that there is no separation and independence of the 

 vacuole walls {" tonoplast" of de Vries) from the peripheral proto- 

 plasm, and no accumulation of water between them. Indeed, he goes 

 so far as to state it as his considered opinion that the important and 

 characteristic feature of aggregation is the swelling of the protoplasm, 

 the vacuolar phenomena being resultant and secondary. In support 

 of this view Akerman again tested a long series of substances and 



