. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ENDOCRINE SYSTEM OF SILKWORM 133 then the activation spread without decrement and could apparently cause the de- velopment of any number of brainless pupae that one incorporated into the chain. But when only the anterior-most animal possessed prothoracic glands, then the activation spread decrementally and only the next adjacent member of the chain received the necessary concentration of prothoracic gland hormone. Just such a difference in the behavior of the two types of preparations would be anticipated if the prothoracic
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ENDOCRINE SYSTEM OF SILKWORM 133 then the activation spread without decrement and could apparently cause the de- velopment of any number of brainless pupae that one incorporated into the chain. But when only the anterior-most animal possessed prothoracic glands, then the activation spread decrementally and only the next adjacent member of the chain received the necessary concentration of prothoracic gland hormone. Just such a difference in the behavior of the two types of preparations would be anticipated if the prothoracic glands of successive individuals can be triggered by the prothoracic gland hormone itself, arising in the preceding member of the chain. Manifestly, within the normal insect the operation of this mechanism would assist the integration of the endocrine mechanism. Since the prothoracic glands are paired organs, whose respective thresholds to brain hormone may differ, the sensi- tivity of one prothoracic gland to the other's hormone would serve to synchronize their secretory activities and couple the two glands into a functional unity. DISCUSSION The experimental results summarized in Figure 11 demonstrate that both pupation and adult development are controlled by an endocrine system consisting of the brain and prothoracic glands. According to the ligation experiments A. PUPATION BEGINNING TO SPIN BEGINNING Or PREPUPUL ST»GE PUPAL MOULT •*. I PROTHORACIC GLANDS REQURED. -10 B. ADULT DEVELOPMENT BEGINNING Of AOULT DEVELOPMENT -f INITIATION OF EYE PIGMENT <f AOULT EyERGENCE. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 189
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
