Digcru-ssion of Egperimeatal Besults 



The res-alts of the monthly toxicity tests for each plot are 

 presented in Tahle 2, The data represent the "ioiicity in mouse xmits per 

 100 grams of siphons or hodies. The graphic interpretation of this 

 information is shown in Figures 1 to 9. The toxicities of "bodies ajid siphons 

 from the same sample have been placed in the same figure. Toxicity cTorres 

 from plots in the same locality have "been combined in one figure. 



The plots studied were typical of the clam beds in Southeastern 

 Alaska in terrain and clam population. However, as was mentioned previously, 

 nine of the plots were located on beaches of known high toxicity in order 

 to provide clams containing determinable quantities of toxin •!;hroughout 

 the year. This was done so that any fluct'jations in toxicity could be 

 determined from mo::ith to month. 



The reactions of the mice which died when injected with the 

 extracts of clam materials (either bodies or siphons) were identical to the 

 reactions described for deaths due to the injection of mussel poison. Two 

 investigators who had worked extensively with mussel poison confirmed this 

 observation. In post-mortem examinations immediately after death, the 

 chambers of the heart were noted to beat rhythmically; this so-called heart 

 block is a characteristic of mussel poisoning. 



The seasonal toxicity characteristics of butter clams are very 

 definitely different from those of mussels, Rytilus calif omi anus , and 

 Washington clams, Saxidomus nuttallii . of California (Sommer and Meyer 1937) 

 and of mussels, Rytilus edulis „ and soft shell clams, Mva arenaria „ of New 

 Brunswick (Medcof, et al,, 19^7). Studies of the California and New 

 Brunswick species indicate that there are short periods in the summer months 

 when they become highly toxic. The toxicity increases rapidly and then 

 diminishes rapidly within a few weeks. During the winter months these 

 species are normally relatively free of ^oxln. In the present survey, 

 except for Plot I, which had relatively non-toxic clams throughout the year, 

 the butter clams from all the beaches showed some degree of toxicity at 

 every saurpling. 



Prom a study of dino flagellates in these waters made dij.ring the 

 sunmier of 19^9, the report of which has not yet been published,-*^ it is 

 known that dinoflagellates of the genus (jop3^u1£lx . a member of which is the 

 causative organism of mussel poison, do abound in the waters along the 

 Alaskan beaches studied. 



The toxicity of the siphons was regularly much greater than that 

 of the bodies. However, the ratio of toxicities of siphons to bodies is 

 not constant. The toxicity of the siphons varies greatly from month to 

 month, while the toxicity of the bodies does not display a similar degree 

 of change. The ratio of the weight of siphons to bodies depends upon the 

 care with which the siphons are removed. The data from three laboratory 



2J A study of diaoflagellates in the waters of Southeastern Alaska 



carried out by Lucile Foster of the George Williams Hooper Foundation 

 In cooperation with the Fieheiy Products Laboratory, 



