2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 39 



tacean blood, in which a special category of cells, the Hardy's ex- 

 plosive corpuscles, corresponding to the insect hyaline hemocytes or 

 coagulocytes, plays a selective part in the inception of the coagulation 

 of the plasma. 



Pattern II. Extrusion of cytoplasmic expansions by hyaline hemo- 

 cytes, with development of cytoplasmic meshworks. Reaction in the 

 plasma in the shape of veils. — On contacting the glass, a category of 

 fragile hyaline hemocytes undergoes alterations that differ from those 

 characterizing pattern I. These corpuscles extrude threadlike cyto- 

 plasmic expansions, sometimes of considerable length. These ex- 

 pansions are highly adhesive to solid particles (dust, chitinous 

 debris), other hemocytes, and physical interfaces (bubbles). These 

 alterations result in formation of cytoplasmic meshworks of various 

 complexity, on which the other kinds of hemocytes are passively 

 agglutinated. 



The reaction in the plasma after these cellular changes occurs in 

 the shape of transparent, elastic, and contractile veils, developed within 

 the cytoplasmic systems built up by the hyaline hemocytes, or in their 

 vicinity. 



In various insects the alterations in the unstable hemocytes are not 

 followed by changes in the plasma, and the modifications of the 

 hemolymph in vitro consist only of a cellular reaction. 



Pattern III. Patterns I and II combined. — Association of the re- 

 actions taking place in patterns I and II characterizes the picture in 

 pattern III. In the same film of hemolymph, hyaline hemocytes send 

 out cytoplasmic expansions (pattern II) while islands of coagulation 

 (pattern I) appear around the body of these corpuscles. When they 

 develop within the veils, which characterize the reaction in the plasma 

 in pattern II, the islands form circular, denser areas centered by the 

 altered unstable corpuscles. 



Pattern IV. No modification in the hyaline hemocytes, or altera- 

 tions not follozved by visible reaction in the plasma, in the optical con- 

 ditions of phase-contrast microscopy. — In the pictures of this pattern, 

 hemocytes resembling in their cytological characters the unstable 

 corpuscles involved in the other patterns do not visibly alter. They 

 appear as pale vesicles containing a few dark particles. In several 

 insects, these corpuscles are the remnants of darker refractile, hyaline, 

 frequently oenocytoid-like hemocytes, which undergo clarification 

 after explosive discharge of a part of their cytoplasm. In the vicinity 

 of these inert or altered hyaline hemocytes, no change can be detected 

 under the phase-contrast microscope in the consistency of the plasma. 



