898 TRANSACTiOJJS OF SECTION K. 



wondered that their capacities speedily declined at such a banquet, and that the 

 velocity-reaction of anabolic synthesis traces a falliiift' curve in spite of the keeping 

 up of all the factors concerned, to wit, terapcratiuv, illumination, and supply of 

 C0„. This decline is not permanent, hut after a period of darkening the power 

 of assimilation returns. I'hysical-chemical parallels can easily be found among 

 cases where the accumulation of the products of a reaction delays the apparent 

 velocity of the I'eaction, but this complicated case in\y be left for further research. 



In relation to assimilation, then, we must say that owing to secondary causes 

 the case is not so clear over the wholiM'ange of temperature as tliat of respiration, 

 but that at medium temperatures we have exactly the same relation between 

 reaction-velocity and temperature. 



AVe may consider now some data upon the combined net result of anabolic and 

 katabolic processes. Such total effects are seen in their clearest form among 

 imicellular saprophytic organisms for whicli we have a few data. Mile. Maltaux 

 and Professor Massart ' have published a very interesting study of the rate of 

 division of the colourless flagellate Chilomo7ias pamma-Aum and of the agents 

 which they say stimulate its cell-division, in particular alcohol and heat. 



They observed under the microscope the time that the actual process of divi- 

 sion into two took at different temperatures. From 29 minutes at 15° C. the 

 time diminished to 12 minutes at 25° C, and further to 5 minutes at 35° C. The 

 velocities of the procedure at the three temperatures 10' C. apart will therefore 

 be in the ratio of 1 : 2'4 : 5'76, which gives a factor of 2'4 for each rise of 10° C. 

 (See fig. 5, Division.) 



Now we are told by the investigators that at 35° C. Chilomonas is on the point 

 of succumbing to the heat, so that the division rate increases right up to the 

 death point, with no sign of an optimum effect. Below 14° C no observations are 

 recorded. 



Here, then, we have throughout the whole range exactly the same primary 

 temperature relation exhibited by the protoplasmic procedure that we should 

 expect for a chemical reaction in a test-tube. 



This division phase is only a part of the life-cycle of the flagellate, and between 

 division it swims about anabolising the food material of the medium and growing 

 to its full size ready for the next division. One wLshes at once to know what i.=f 

 the eff"ect of the temperature upon the length of the life-cycle. Is the whole rate 

 of metabolism quickened in the same way as the particular section concerned 

 with actual division ? Of course a motilt; flagellate cannot be followed and its 

 life-cycle directly timed, but the information was obtained by estimating carefully 

 what percentage of individuals was in a state of actual division at each tempera- 

 ture. It was found that always 4 per cent, were dividing, whatever the tem- 

 perature. This proves that the whole life-cycle is shortened In exactly the same 

 proportion as the process of division at each temperature, and that it is just 

 twenty-five times as long. Therefore the life-cycle is 125 mins. at 35° C. and 

 725 mins. at 15° C, so that here, again, we have the physical-chemical relation 

 with a factor of 2-4 for each rise of 10° C. 



■ In this paper of Maltaux and Massart these relations are not considered a« 

 the manifestation of physical-chemical principles, but are regarded as reactions to 

 stimuli ; and the paper contains a number of experiments upon the effect of 

 sudden changes of temperature upon the occurrence of division. As far as one 

 can make out from inspection of the scattered literature, it does seem established 

 that sudden changes of temperature act as stimuli in the strict sense of the word. 

 In many investigations one finds it stated that a quick change of temperature 

 produced a certain reaction which a slow change of temperature failed to evoke. 

 Usually all the phenomena are treated in terms of stimulation, and the absence 

 of reaction with slow change of temperature is regarded as secondary. Were 

 it not for the specific stimulatory effects of quick change, which are not difficult 

 to comprehend as a phenomenon sui cjeneris, I hardly think so general a tacit 

 acquiescencewould have been extended by botanists to the view that all enduring 



» Maltaux and M&ss&Td.Itecneil fie VTnslHnt lotaniq^ne Jiriixcllrg, tome \'u 190G, 



