AND EMBRYOLOGY OF FROGS. 387 



lowing are the records : March 5th, April 5th, '90. The eggs of 

 Ratia clainitans are not so certainly referred to as its adult, and I 

 have only strong probability showing them to belong to that 

 species. The bunches much resemble those of Ra7ia halecina, 

 but the eggs are larger and the jelly firmer. Those I have found 

 were also attached to twigs of bushes, which is not always the case 

 in Rana halecina. 



The toad {Bufo lentiginosiis) in this latitude lays very late in 

 the spring. The eggs are easily distinguished from the frog's, as 

 they are laid in long strings, often yards in length, the eggs 

 arranged (generally) in a single row. They were recorded April 

 14th, 1890, April 5th and 6th, 189 1. The best localities seem to 

 be those parts of rivers or streams where the water backs up, and 

 to one side protected by a bar, so that the eggs are not carried 

 away by the water, and where the water itself is often exceedingly 

 warm. Copulating individuals are easily obtained, and they con- 

 tinue to lay in confinement. 



II.— Laying in Confinement.— If frogs are caught at the height 

 of the breeding season, they can often be got to lay in confine- 

 ment. The surest way is to get the paired individuals, frightening 

 them as Httle as possible, and placing them in dishes or aquaria 

 containing the requisite amount of water. Only once have I had 

 the wood-frog lay in the laboratory, although with proper precau- 

 tion there seem to be no very great difficulties of obtaining in this 

 way the eggs of the species. A single large bunch of eggs were 

 laid by this pair during the night, which developed normally. 



By far the best and easiest eggs to be obtained, by bringing 

 frogs into the laboratory, are those of the tree-frog named above. 

 They will continue to lay small bunches of eggs for as much as 

 twenty-four hours after catching them. By removing the bunches 

 as fast as laid, an exact record may be kept as to the age of 

 the different lots. Moreover, the eggs of these species are small, 

 and the jelly clear, so that they are well adapted for study of the 

 segmentation stages under the microscope. The distinction be- 

 tween the cells derived from the black (animal) pole, and those 

 from the yellow (vegitative) pole, is very sharp, and the fate of 

 the cells more easily traced through the later stages of segmenta- 

 tion. Toads brought into the laboratory, and placed under proper 



