pringsheim's research ks on chlorophyll. 83 



signs betraying the existence of some peculiar substance. 

 If a cell of Spirogyra crassa, or other large species rich in 

 hypochlorin, be slightly injured, eith-^r by mechanical pres- 

 sure or by warming (up to 30° — 40° "C. according to the 

 species), so that but little disturbance of cell content is 

 produced, there are seen in the projections at the edge of the 

 chlorophyll-bands and beside the amylum-bodies, that is, 

 at the exact position Avhere hypochlorin becomes visible 

 when an acid is employed, laiige clear vacuole-like spaces 

 filled with strongly refractive oil-like matter (fig. 13). These, 

 which have not been hitherto generally noticed, differ from 

 the small fat-particles abundantly distributed through the 

 bands by their larger size, more fluid content, and the pos- 

 session of a limiting pellicle. A slight contraction of the 

 band in breadth is associated with their appearance, and the 

 projections on the edge of the band disappear. After very 

 slight warming the large vacuoles may be readily observed 

 at the edge of the band to rupture their skin, and their fluid 

 content is disseminated in the surrounding protoplasm lining 

 the cell wall (fig. 12). In large species of ^pirogijra a 

 spontaneous coalescence of the vacuoles may often be 

 witnessed. 



The position of these vacuoles leads to the conjecture that 

 it is their oily content which forms the hypochlorin excre- 

 scences, a conjecture quite conformable with the easy destruct- 

 ibility of hypochlorin in green tissues. For this accumula- 

 tion of oily matter in vacuoles, the ready escape of the same, 

 and its dissemination in the protoplasm under slight me- 

 chanical or thermal influences, affords an explanation of 

 those cases where the hypochlorin reaction is absent or 

 suppressed, and further explains the results, now to be 

 described, that follow when green tissues previously warmed 

 in water are treated with dilute acids. After such treatment 

 the hypochlorin reaction is suppressed. 



If a tissue which has been warmed in water, and in 

 which the characteristic exudations have been developed, be 

 treated with dilute hypochloric acid, no hypochlorin masses 

 are formed, neither on the coloured drops nor on the ground- 

 substance of the chlorophyll-corpuscle, provided that the 

 duration of warming and the temperature have been suffi- 

 cient for the tissue and species examined. Usually the only 

 visible effect is a slight change to a browner tint of the coloured 

 drops. The time and temperature limits vary considerably 

 with the species. Thus, for Mesocarpus scalaris, which is 

 very rich in hypochlorin, five minutes^ exposure to a tem- 

 perature of 42° — 43° C. suffices ; Cladoplwra requires five to 



