NO. 6  HEMOLYMPH COAGULATION IN INSECTS—GREGOIRE a5 
with regard to the pattern of coagulation predominant or representa- 
tive of the taxonomic category. 
Such consistency suggests that the patterns of hemolymph coagu- 
lation are a character of taxonomic significance (in a broad sense). 
Whether that type of character is of more or less applicability in 
phylogenetical controversies, is a question left to competent phylo- 
geneticists. It might, however, be stressed that the process of hemo- 
lymph coagulation is in no way related directly to any type of struc- 
tural or ethological criteria commonly used for defining and grouping 
taxonomic categories. It is therefore of interest to check tentatively 
some taxonomic relationships on the basis of the presented data. 
5. As pointed out elsewhere (Grégoire, 1955a, pp. 136-137), ran- 
dom coincidence does not seem to be entirely responsible for explain- 
ing some correlations between phylogenetic position of certain groups 
of insects and microscopical aspect of the coagulation of their hemo- 
lymph. In this respect, the Neotropical material examined here sup- 
ports former tentative suggestions concerning most of these corre- 
lations.” 
Pattern I has been heretofore uniformly recorded in Blattodea and 
in the other groups ranged within the orthopteroid complex. The 
mechanism involved in this pattern is identical to one of the types of 
coagulation described by Hardy (1892), Tait (1910, 1911), Tait and 
Gunn (1918), Numanoi (1938), and Grégoire (1955b) in crustacean 
blood, in which a special category of cells, the Hardy’s explosive cor- 
puscles, corresponding to the insect hyaline hemocytes or coagulo- 
cytes (Grégoire and Florkin, 1950), play a selective part in the in- 
ception of the coagulation of the plasma. 
Pattern I has also been recorded among various unrelated groups 
of insects, especially in groups characterized by the retention of 
various primitive characters, such as the Homoptera. In this respect, 
the present study has brought information on groups not represented 
in the material previously investigated. 
From these data, pattern I might be considered as a generalized 
primitive mechanism of coagulation of insect hemolymph. 
The mechanism of coagulation illustrated in pattern II has been 
observed, unmixed or predominant, in relatively recent groups of 
7 After the completion of this paper, the patterns of coagulation were recorded 
in 400 insects collected in September 1956 at Tingo Maria (Peru) and in Octo- 
ber 1956 on Barro Colorado Island. The results are in agreement with those 
reported here, with regard to the predominance of one of the patterns in the 
following groups: Orthopteroid complex, Hemiptera, Homoptera, Scarabaeidae, 
Tenebrionidae, Cerambycidae, Curculionidae, Vespidae, and Diptera. 
