No. 7.— CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY 
OF THE MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD 
COLLEGE, UNDER THE DIRECTION OF E. L. MARK, No. 145. 
The Changes which occur in the Muscles of a Beetle, Thymalus 
marginicollis Chevr., during Metamorphosis. 
By Ropert 8. BREED. 
TABLE OF CONTENTS. 
PAGE PAGE 
MaUrOGuCctiOne 5-4 fee bs ee BLT a. Muscles that pass unal- 
fare il—Anatomy . .. .. . « olf tered from the larva to 
A. Historical Survey ... . 818 the imago . . 349 
®. Observations .°. . .', . 819 b. Metamorphosis of faneal 
1. Material Ar oo Bi te hee SOLS muscles into 
2. Methods 9 u.:-. 821 (1). Muscles of the wing 
3. Anatomical changes of the CVO tas 5.33 patel 349 
MIURCIeR st25% ay" ag Oak a. Larval period . . . 349 
a. Metathorax .. . 322 B. Pupal period . . . 3538 
(1). Dorsal antero- pontarios y. Imaginal period . . 855 
Miuscles? si... 3 323 (2). Muscles of theleg type 356 
(2). Lateral dorso- ventral a. Larval period ... . 357 
museles) +. si \- . 824 B: Pupal period. ..... 357 
(3). Ventral antero- neste y. Imaginal period . . 358 
rior muscles . . . 3836 (3). Metamorphosis of the 
by Mesothorax 0%... « *. 837 intestinal muscles. . 358 
(Me ig) 010). >. ae ee =| c. Histolysis of the larval 
Gubeag i a's Ae lh, oc’! 4 388 muscles. .) ..) 361 
6, AbdomMeMr fog i ysiss e-y > 888 d. Histogenesis of the imag- 
j. Appendages, =~ «>. |. 339 inal muscles . . . 38638 
4. Discussion of results. . . 339 3. Observations on other Cole- 
Part Il.— Histology ... . . 840 optera: 2075 0.0 Peed 
A. Historical survey . . . . 840} OC. Discussion of results . . . 366 
Ba Observations < os. so) a. OEP SUMIMAEY | tse hr oe nce ee ae, OL 
I. Methods .: >. -. O47) Bibliography §s.5. 6 ces 8 BLS 
2. Histological bianees of the Explanation of plates . . . . . 880 
miuscleay 4 )i5, o2)- ate 2 S48 
Introduction. 
While there have been numerous researches on the changes which 
occur during the metamorphosis of insects, many points remain not 
clearly understood, and others are in dispute. The present investigation 
VOL. XL.— NO. 7 1 
