382 R. W. GLASER AND J. W. CHAPMAN. 



of which we are at present ignorant is responsible for the frequent 

 failures. We have performed a sufficient number (15) of these 

 recrystallization experiments, however, to warrant a report of 

 the results. 



Crystallizable proteins are, of course, not uncommon. Haemo- 

 globin is perhaps the best known example in animals and the 

 aleurin grains a well known example in plants. By fractional 

 precipitation with magnesium sulphate or sodium chloride two 

 or three separate crystalline proteins can be obtained from 

 the albumen of the hen's egg. In insects, by the evaporation 

 of blood with a trace of acetic acid, beautiful protein crystals 

 can be obtained, different in every species. 



Our view regarding the nature of the polyhedral bodies may 

 therefore be summarized as follows: During the course of the 

 disease the virus disintegrates the nuclear material in such a 

 way that crystal-like bodies called polyhedral bodies or polyhedra 

 are synthesized out of the disintegrating proteins. Just how the 

 process from nuclear material to polyhedra takes place .is at 

 present unknown. At any rate, from our morphological observa- 

 tions, experimental infection data (published elsewhere) and 

 from our chemical studies here presented, it seems clear that the 

 polyhedra are nucleoprotein degeneration-products and not 

 organisms responsible for a series of insect diseases. 



f SUMMARY. 



1. Polyhedral bodies are found in many different species of 

 lepidopterous larvae. 



2. The bodies are specific for a certain type of disease. 



3. The polyhedra vary in size in the different species. 



4. There exists a striking similarity in shape between the 

 polyhedra found in different species. 



5. The polyhedra are structurally complicated. 



6. They arise in the nuclei of certain tissue cells. 



7. Cytoplasmic inclusions are found in certain diseases of 

 higher animals. 



8. Nuclear inclusions have not been known previously. 



9. The polyhedra are nucleoprotein crystal-like degeneration- 

 products and not organisms. 



