266 Proceedings of Indiana Academy of Science 



behavior in the plant concerned. Therefore a study of pollen behavior, 

 as far as possible, has been made in the field in certain cases for the 

 sake of comparison with the laboratory experimentation. It is expected 

 to extend this phase of the work. 



Since my third paper on this topic I have increased the number of 

 plants to 561. In all cases thus far the pollen has been tested in the 

 various solutions referred to in my last paper. As yet no specimen has 

 been found which for number of germ tubes produced is as prolific as 

 Malva crispa referred to in my previous paper\ Some of the pollen 

 reported in this paper refused to germinate under any of the laboratory 

 conditions that were provided while in other cases germination occurred 

 under precisely the same arrangements. In this last study no case of 

 more than one pollen tube from a single grain has been observed. Pri- 

 7nula ohconica showed luxurious germination in most cases and under 

 ordinary conditions is a favorable specimen for investigation. This was 

 notable in as much as below and immediately above 10 per cent of cane 

 sugar active germination was observed, but at 10 per cent none oc- 

 curred in the specimens studied. This corroborates the findings here- 

 tofore brought out in certain other cases mentioned during these studies 

 and it deserves further attention. There arises here also certain ques- 

 tions concerning the difference in the amount of time required for the 

 commencment of germination aside from the influence of membranal 

 valuation. This I have found to be very different in the various pollens 

 studied and constitutes a considerable problem in itself. 



PROTOPLASMIC STREAMING. 

 F. M. Andrews, Indiana University. 



The idea of this chemical study in Rhizopiis nigricans was to ascer- 

 tain the behavior of the plant when plasmolysed in different degrees and 

 the response of the protoplasmic movements when in this condition. It 

 is well known that some plants when plasmolysed by certain substances 

 may remain living for only a short time while others will live for weeks 

 in this condition". It is the intention to carry out this study by using 

 various representatives from the six groups of metals as well as certain 

 organic substances such as sugar and glycerine. 



In the first experiments a 20 per cent solution of cane sugar was 

 used. In these experiments a rather sudden plasmolysis resulted, in the 

 time it was maintained, in a slowing of the streaming from a speed of 

 three mm. per minute to one-tenth mm. per minute. When the normal 

 hydrostatic pressure was restored the normal velocity of protoplasmic 

 streaming above mentioned in these specimens was finally restored. In 

 the series of specimens experimented with in this way, however, three 

 hours elapsed before the normal speed was regained. The question still 

 remains as to whether or not a full cessation of streaming could be 



> Andrews, F. M. Studies on pollen— III. Proc. Ind. Acad. Sci., 1920. p. 155-156. 

 = PfeflEer, W. PflanzonphysioloKie 2te Auk. 1904, Bd. II, p. :530. 



