Tlie Relations between Marine Animai and Vegetable Life. 



383 



paper already leferred to', cousiderable variations in tlie amouuts 

 of free oxygen and carbonic acid dissolved in the water bave bat 

 little influence on the growth of the larva;. 



The results obtained are given in the following table. In all 

 cases the water was heated in a large flask filled up to the neck, 

 and on the temperature reaching the desired point, this flask was 

 placed under a stream of cold water, so as to cool its contents as 

 rapidly as possible. The water was then poured into a jar, and 

 allowed to stand for 24 hours before the introd action of the fer- 

 tilised ova. 



From these figures we see that in five out of the seveu ex- 

 periments made, there was a very considerable increase in the size 

 of the larvte, this increase ranging from 5.8 to Vò.^%. In every 

 case but one also the percentage of fertilised ova reaching the larvai 

 stage was equal to or greater than the normal. It will be seen that 

 two or three experiments were made at each of the three tempera- 

 tures 100", 70° or 77", and 50°, and probably the ett'ect produced 

 is on an average about the sanie for each temperature. In the ex- 

 periment made at 77" the larvìe were apparently unafifected, but this 

 result was probably due to some unknown source of error. Also in 

 the first experiment given in the table the larvas were only slightly 

 increased in size, and the number of ova reaching the larvai stage 

 was very small. This was probably due to the water used being 

 not only heated to 100°, but actually boiled for two or three minutes, 

 whereby niuch more of the dissolved gases was driven off. The 

 heating of the v/ater to 100° probably exerts two opposing influences 

 on the quality of th'e water, which more or less neutralise each other. 



1 ibid. pag. 597. 



