1916.] The Third Indian Science Congress. C vii 



a needle or a soft brush, the valve opens suddenly and the concave walls 



t ZLT V Z Creatmg a l aVit ?' inSi ^ Which is fiIled wifch ™^ ««eked 

 ™-j£T 8 -? ° P t? m ° Uth - • Immedi ately the valve falls back to it, 

 original position If an organism is the cause of irritation, it is forcibly 

 sucked in with the water. During reaction to irritation the valve be- 

 thuTformeT 8 ir "table hairs are laid in the hollow of the h. . 



Darwin did not succeed in making the bladders react to irritation 

 because he tailed to recognize that the bladders are irritable only when 

 they are m the hungry condition and do not react when they are full. 

 *mce those m the latter condition form the majority, it is presumed that 

 he experimented on full bladders. The bladders in which* the "article.! 

 of glass and pieces of boxwood suddenly disappeared, should have been 

 ZnHSHJ^Si <2*J*«* . Insect • • • «»»*■. P- 328). The 



hungr 



pressing out the contents carefully with a pair of pincers 3 or 4 time,:, 

 after which they will be found to react to irritation 



r, a ^ Th Lr la ul°L bet . ween the structure and function of the different 

 parts of the bladders is under investigation. 



The Floating Plants of Lower Bengal and their Adaptations. 



By M. S. Ramaswami. 



An 



gamic vegetation of the stagnant fresh-water ponds of Lower Bengal was 

 presented. Those collected and studied by the author have been classi- 

 fied into groups— the classification being based primarily on the degree of 

 notation and secondarily on the nature and functions of the flotativ 

 adaptations. Several interesting kinds were described in detail. 



Besides giving a rather comprehensive list of the floating species, 

 the author also described a few plants which though not hitherto known 

 to be floating were nevertheless seen by him to be actually so. These he 

 found to have developed certain structures ordinarily adapted to a floating 

 habit. Such apparatus were also described and compared with the land 

 forms of the same species. 



Importance of Soil- Aeration in Forestry 1 .—^ R. S. Hole. 



This paper, which was illustrated by lantern slides, emphasized a 

 point which has not yet attracted the attention it appears to deserve, viz. . 

 the damage that may be done to the seedlings of forest trees in India by 

 insufficient soil-aeration when the physical condition of the soil i 

 apparently suitable for growth, and when the soil, although moist, is far 

 from being saturated with water. The results of experiments recent h 

 carried out at Dehra Dun were described dealing with the causes of the 

 death and dying-back of Sal (Shorea robusta) seedlings. All the facts 

 "itherto ascertained indicate that an injurious soil factor is chiefly 

 ' ^sponsible for the unsatisfactory development of Sal seedlings by causing 

 high mortality daring the rains, and subsequently a high percentage of 

 deaths from drought owing to poor root development. Clearing the 

 forest growth and exposing the soil to sun and air produces the eondi- 

 r ions necessary for the vigorous and thoroughly healthy growth of Sal 

 seedlings, provided that the area cleared is sufficiently small to ensure the 

 light side-shade necessary for protection from frost. As the injurious 

 factor can be put out of action by sufficiently good soil-aeration it may . 

 for the present, be conveniently termed bad soil-aeration. Further work 



1 This paper will be published in extenso in the Congress number of 

 the Agrj iltural Journal of India. 



