1 66 Gardner — Studies on Grcnvth and Cell 



increased growth. From the tables can readily be seen the 

 increase in growth of the roots, in solutions of one-fifth, one- 

 tenth and one-twentieth per cent above the control. 



HCl. — Seedlings will germinate, but will live, for only a 

 comparatively short time in solutions of HCl of one or two 

 per cent. The neutral point is reached at a one-half per cent 

 solution. All weaker solutions such as one-fourth per cent, 

 one-fifth per cent, one-tenth per cent act as stimulants. 



(NH'^.^CO^. — In using (NHj)2C03 it was found that only when 

 very weak solutions were used, was it possible to obtain any 

 results. Germination never occurred in solution of one-half 

 per cent, or one-fourth or even one-tenth per cent. Seeds 

 germinate and live in a one-thirtieth per cent solution, yet this 

 growth is a retarded one. The neutral point is reached in 

 solution of about one-fiftieth per cent and all weaker solutions 

 act as stimulants. One seventy-fifth per cent and one one- 

 hundreth per cent were used, both causing a marked increase 

 in growth. 



So we must conclude that it is possible to obtain chemical 

 solutions of such a strength that they act as nutritive stimu- 

 lants, causing an acceleration in the growth — also to find the 

 points of these same solutions which can be regarded as 

 neutral, and above which point these solutions have a toxic 

 or retarding action. 



C. Cell Division. 



Within the past thirty years cell division has been a favorite 

 study for cytologists. There has always been much difference 

 of opinion amongst writers as to what is the correct explana- 

 tion of their observations. Before stating my own observa- 

 tions and conclusions, a short review of the more recent 

 papers will be given from which can be seen how greatly 

 authors differ on the subject. 



A valuable cytological paper which reviews and condenses 



