Formerly held opinions with regard to an excessive sensitiveness of the eggs against 

 changes in ten^erature have been found to be unfounded, according to He in . 



The counting of the eggs in the incubator is always easier than the counting of the 

 broodlings. And since losses are negligible in eyed eggs it is of advantage to divide 

 the brood among the different incubators while still in this stage, but not all too 

 shortly before the time of hatching. 



The following four methods for counting eggs are simple and practical: 



(1) Weigh out 1000 eggs upon an apothecary scale, using this weight as a 

 unit for larger amounts, weighed out upon a larger scale. Since the 

 weight of eggs is variable, on account of the different sizes of eggs, 

 I abstain from quoting figures, but en^hasize that the unit weight 

 has to be ascertained from the eggs of different stocks. 



(2) Measure (in a graduated glass) the cubic volume of 1000 eggs and then 

 count the eggs out with larger measures, 'flie advantage of this method 

 is that the eggs can be siphoned out. While the cubic unit has also to 

 be measured for each separate stock, I found that with small eggs the 

 differences are negligible. For marftne eggs I found almost invariably 

 the following figures per 1000 eggs: 



Coregonus generosus: 25 cubic centimeters. 



» albula : 9 " " 



" lavaretus: 40 " " 

 For trout eggs there is also a cup measure of about 50 com. in use, 

 with a wire-screen bottom. The counted-out number of eggs from the 

 first serves as unit for all further measurements. 



(3) By means of the overflow apparatus (Fig. 35) may be determined how much 

 water is displaced by 1,000 eggs which are transferred without water into 

 the funnel and sink into the lower vessel filled with water. The eggs are 

 transferred with a spoon net. The Schillinger Measure Glass works on the 

 same pronciple. To lessen the manipulation, a rubber hose may be connected 

 to the overflow tube and held high until the end of the filling. The 

 water displacement (true volume of 1,000 eggs) may also be easily found from 

 the third power of the egg diameter in centimeters by multiplication wi^h 

 524: True Volume (water displacement) of 1,000 eggs = d3 x 524. Finally 

 to be regarded is what has been said in methods 1 and 2. 



(4) By means of a hard rubber plate (Brandstetter Counting Plate, obtainable 

 at F. Greiner, Munich, Uathilden Strasse), which has a definite number 



of hemispherical depressions with bottom perforations. The depressions 

 are the size of a trout egg. The plate has a handle and can transfer a 

 definite number of eggs. The great advantage is independence of individual 

 size of an egg. Only eggs the size of trout eggs can be measured. 



119 



