206 REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



Table No. 24. 



*Shoinng the effect of sunlight upon the ^percentage of increase in 

 size of fourth stage lobsters. 



In Sunlight. 



Fourth Stage, j Fifth Stage. Gain per cent. 



14.5 mm. 

 15.0 mm. 

 14.3 mm. 

 14.7 mm. 

 15.5 mm. 

 15.2 mm. 



17.0 mm. 

 16.8 mm. 

 16.5 mm. 

 17.0 mm. 

 17.5 mm. 

 17.2 mm. 



17.2 

 12.0 

 16.0 

 15.6 

 12.9 

 13.1 



In Twilight. 



Average 



14.4 



14. 1 mm. 

 15.5 mm. 

 14 . 5 mm. 

 14.0 mm. 

 14,0 mm., 

 14.5 mm. 

 14.3 mm. 



Fourth Stage. Fifth Stage. Gain per cen 



15.7 mm. 

 17.5 mm. 

 17.5 mm. 



17.5 mm. 



17.6 mm. 

 17.0 mm. 

 16.5 mm. 



Average 



11.3 

 12.9 

 20.6 

 25.0 

 25 . 7 

 17.2 

 15.3 



18.2 



*A11 lobsters recorded pa.ssed from the third to the fourth stage on the same day, June 23, 

 and were thus subjected to the same degree of water temperature whose variation, as we know, 

 is able to make a great difference in the duration of the stage-period, as also in the amount of 

 increase in size. Food conditions were also identical in the case of each group. 



In this regard attention may be directed once more to Table No. 

 7. Here it is evident, when we note also the results given in Table 

 No. 5, that the stage-periods of Emmel's normal 1905 lobsters are 

 longer than the average; also that the percentage of increase in length 

 is generally less. It is certainly worthy of notice that these lobsters^ 

 during the early stages, were confined in wire cages (Plate XL), 

 and that the covering which was placed over them was insufficient 

 to exclude all of the light; at least they were by no means as well 

 protected as the young lobsters confined in the wooden compartment 

 cars in which, as will be noted from Table No. 5, the duration of the 

 stage-periods was less (1904 and 1905 group). 



Not only may the influence of light act directly upon the metabolic 

 activity, and thus upon the rate of development, but also indirectly 

 by favoring the growth of various parasites on the body and ap- 

 pendages. This subject will be considered more appropriately in 

 the following discussion. 



