OKIGIN OF 'independent' LENSES 353 



to consider as similar to (or possibly identical with?) an enzyme 

 reaction. In other words it might be imagined that ophthal- 

 moblastic substance (and most likely potential retina) when in 

 contact with epidermis acts as a catalyzer for the chemical reac- 

 tions necessary for the transformation of the latter into a lens. 



Very strong support is lent to these conclusions by the results 

 of some more recent experiments in which I have employed a 

 modification of one of my methods. By employing weak solu- 

 tions of acetone and long exposures I expected that embryos 

 might thus result in which less destruction and more dissocia- 

 tion would be noted. And such was actually found to be the 

 case. 



While some of the eggs so treated have given rise to synoph- 

 thalmic or monophthalmic monsters, others have developed into 

 embryos with two large, grotesquely protruding eyes in the 

 usual lateral position in the head (fig. 2). Some of the embryos 

 from these experiments possess two ill-formed eyes of medium 

 size, one of which may often be far protruding, or in some cases 

 one or both eyes may already on macroscopic examination ex- 

 hibit evidence of dissociation, the pigment layer being either 

 partly duplicated (fig. 1), or fragments of it being observable 

 between or behind the eyes. Examination of sections shows that 

 these eyes are elongate and ovoid in shape and it seems clear 

 that during their formation some forces must have been acting 

 which tended to disintegrate and dissociate the anlage from which 

 they have developed (blastolysis) . 



A detailed description of the microscopic anatomy of such 

 'blastolytic eyes' is reserved for another publication, soon to fol- 

 low. For the present it will suffice to state that in such embryos 

 a number of free lenses of various sizes often are found in the 

 head region on examination in toto, while each one of the eyes 

 may possess a lens of its own in contact with the optic cup. 

 Examination of sections of some of these embryos, however, dis- 

 closes a most surprising multitude of small lentoids anterior to 

 the eyes. 



A brief description of sections through the anterior part of the 

 head of one such embryo may now follow. Already in toto 



