82 LEWIS R. GARY. 



during this time and they continued to reproduce by laceration 

 throughout the year, although no embryos were ever set free 

 during either of the breeding seasons. 



The specimens of A. tagetes studied were obtained in 1909, 

 during a stay at the Bermuda Biological Station. 



A. annulata was obtained during the past summer while the 

 writer was at the laboratory of the Carnegie Institution of 

 Washington at Dry Tortugas, Florida. 



The two last-mentioned forms were studied in aquaria in the 

 laboratory only. 



Material of the four species was preserved, after being narcot- 

 ized in magnesium sulfate, in a number of fixing reagents; of 

 which Petrunkewitsch's fluid and Bouin's fluid gave the best 

 results. All of the Aiptasmt cut readily after being imbedded 

 in paraffin in the usual manner, while the mesoglea of the Cylistas 

 proved so refractory that double imbedding in celloidin and 

 paraffin was necessary in order to secure an unbroken series of 

 sections. 



In common with the tissues of most actinians, many of the 

 hsematoxylin stains were highly selective, staining the ectoderm 

 much more heavily that the endoderm so that by using an alco- 

 holic solution of eosin as a counter stain after Delafield's hsema- 

 toxylin there resulted an absolutely certain color differentiation 

 between the two tissues by means of which any question of the 

 origin of a certain structure could be determined by its staining 

 reaction. 



GENERAL ACCOUNT OF THE PROCESS OF LACERATION. 



As has been described by Andres (1882), the beginning of the 

 process of laceration is characterized by a certain part of the 

 base of an actinian becoming very firmly attached to the sub- 

 stratum while the animal as a whole moves away from the point 

 which is thus relatively immovably attached. As a result the 

 tissues about this point become strongly stretched and attenuated. 

 With the continuation of the contraction, there finally comes a 

 rupture of the tissues at some little distance from the free border 

 of the disc so that the resulting laceration piece has usually an 

 appearance such as is shown in Fig. i, Plate I., which represents 

 a fragment from the base of a specimen of A . pallida immediately 



