sTriMKs (»\ i'()i,i,i;\. 111. 



F. M. Ankukws. IiidiiiiiM riiivcrsity. 



Siii<-(> tli(> ;ii)ii(':ir:iii((> of my second contribution on tlio study of pollen I 

 li.-nc continued my invest iir.-i lion on this subject and luivo added a considcr- 

 .•il>le nundier of plants to those already studied in ways mentioned in my 

 previous paiiei-s. As the work has pro-ressed certain new methods have 

 > n.i,'i,'ested themselves as exitedient or in many cases as necessary for the 

 inoiier advance of the work. One former method of allowing pollen to be 

 l)l;iced for siermination in the desired solution between a slide and cover- 

 iiiass is. while often sivluK results, unfair since certain life processes can 

 not nornnilly be carried out under these conditions. Tlie use of an ordinary 

 ulass riuR cell cemented to a slide and havini; the pollen for investigation 

 in a hanging drop also served in many cases l.nt :iliowe(l of no regulation of 

 temperature by an exchange of aii- in the ways desired. A common gas 

 chamber served the purpose better and (.bviated the ditliculty just men- 

 tioned and also allowed of certain otlu-r f(n-ms nf experimentation, not 

 i:ossible with the glass ring cell, that 1 hope to investigate later on. In 

 this last type of culture cell, as here used, it was necessary to use wet 

 niter pai)er in the cell or a small (piantity of water to prevent the specimen 

 from drying up. All the culture cells mentioned thus far had the disad- 

 vantage of allowing only one experiment or culture to be so arranged at 

 ( ne time. To offset this the glass ring sell was used in large numbers but 

 individual cultures made in this fashion reipiire a great deal of extra work 

 and are not conducive either to convenience or accuracy. In some cases at 

 lirst when an extra large number of cultures were to be made I suppli- 

 niented the glass culture ring apparatus by cells made of filter paper and 

 kept moist in damp air under a bell jar. These latter, how(>ver, were much 

 less satisfactory for various evident reasons. 



Since my second contribution on this subject I have increased the number 

 of plants whose pollen I have studied from 48."i to 540. In the case of all 

 of these 540 plants I have tried to grow the pollen in the following solutions : 

 distilled water and cane sugar of 1%, 59^. 107^;. 15%. 20%, 30%, 40%, 

 'tO'/c and 60%. A great many, of course, did not grow but many did. The 

 pollen of all of these 540 plants were experimented with in this way and 

 given a trial even though, as is well known, some few of them have not 

 yielded results in this way. Of these 540 phanerogams only the pollen of 

 live i»roduced more than one tube on germination. This is very different 

 from some pollen which produces many tubes on germination as in the case 

 of .Malva crispa. Of all the 540 plants I found only one whose pollen tube 

 branched. That was the pollen of Caladium bicolor one of whose pollen 

 tubes branched three times and two of whose pollen tubes branched twice. 

 The record of this plant is as follows, viz : In distilled water ten pollen 

 grains in one hundred germinated. In the cane sugar solutions 21 germin- 

 ated in the 1% ; 4 in 5% : in lO'/r : 3 in 157r : 27 in 20^/r : 15 in 30% ; 3 

 in 40% ; in 50%. and in (>0%. The pollen in this exi)erimeut was all 

 of the same age and grown under exactly the same conditions. The first 

 jioint of interest, therefore, is that in 10% none grew while just above and 



