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being attached close together on 6 parallel hairs. II. (c) Some capitis, 
in a wristlet, laid 476 eggs on 8 hair-grids, chiefly on certain hairs, but 
the eggs were mostly separated by distinct intervals. ( d ) Some corporis, 
in the thermostat at 31° C., laid 356 eggs on 4 hair-grids, many of 
these were in close aggregations, but many were scattered as in capitis. 
It would appear therefore that corporis, under experimental con¬ 
ditions, tends to lay its eggs more closely aggregated than does capitis. 
Nevertheless, as shown in Fig. 5 (p. 122), capitis at times packs its 
eggs very closely under natural conditions, therefore the difference is 
inconstant. 
The Laying of Unfertilized Eggs. 
That lice lay unfertilized eggs has been repeatedly observed; in 
the absence of a male they will lay numerous eggs which soon shrivel 
up. Oviposition continues, therefore, irrespective of fecundation as 
Bacot has also observed. The number of unfecundated eggs laid by 
a female is governed by the same conditions affecting fertile eggs; 
unfertilized or fertile eggs may be laid beginning about 24 hours after 
the emergence of the female from the third larval skin. 
Hindle, Harrison and myself have failed to obtain any evidence of 
the existence of parthenogenesis in lice. 
SUMMARY REGARDING OVIPOSITION. 
1. The temperature at which lice are maintained greatly influences 
oviposition. They do not lay at a temperature below 20° C.; the 
optimum lies at about 32° C., although they mil lay at 37° C. Infested 
persons who remove their clothing at night, as practical experience 
has shown, become less heavily infested than persons wearing their 
clothing continuously, because the periodic cooling of the clothing 
and the therein contained lice necessarily leads to the insects’ progeny 
being restricted. 
2. The fertility of Pediculus humanus (corporis) has been greatly 
underestimated. Under optimum natural conditions a female may 
lay 275 to 300 eggs; the average number laid per day during the whole 
oviposition period being about 10. 
Two experiments made with the wristlet method (see p. 107) 
indicate that capitis may lay more eggs than has hitherto been supposed, 
the females having laid up to 8 and 9 eggs apiece on some days. 
3. Oviposition usually begins 24-36 hours after the adult female 
emerges from the third larval skin. The eggs may be either fertilized 
