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THE ANATOMY AND BIOLOGY OF THE PARASITIC 
A P HELEN CHI. 
By F. H. STEWART, M.A, D.Sc., M.D., 
Major , Indian Medical Service. 
{From the Quick Laboratory , University of Cambridge.) 
(With Figs. 1, 2 on PI. VIII and Figs. 3-32 in Text.) 
CONTENTS. 
PAGE 
I. The parasitic species of the genus Aphelenchus and their discovery . 160 
II. Distribution of the parasites and the diseases caused by them . . 161 
III. Specific distinctness of A. fragariae, A. olesistus, and A. phyllophagus 
n. sp. . . . . . . . . . . 162 
IV. A. phyllophagus n.sp., anatomy of the adult . . . . . 163 
V. A. phyllophagus, the egg and larval development . . . . 165 
VI. A. olesistus R.B., anatomy . . . . . . . . 169 
VII. A. fragariae R.B., anatomy ........ 169 
VIII. Comparative anatomy of (a) the oesophagus and salivary glands, ( b ) the 
renette, (c) the vaginae, in the genus Aphelenchus . . . . 169 
IX. Biology of the parasitic Aphelenchi 
A. Their definitive habitat . . . . . . . 172 
B. Besting stage in the soil . . . . . . . 174 
C. Stage of invasion ........ 175 
D. Mode of entry into the definitive habitat . . . . 176 
E. Influence of atmospheric humidity, and of previous disease or 
injury of the host plant, in assisting migration of the parasite. 
Immunity . . . . . . . . . 176 
X. Methods of combating the disease . . . . . . . 177 
XI. Technique ........... 177 
Summary . . . . . . . . . . . 178 
I. THE PARASITIC SPECIES OF THE GENUS APHELENCHUS AND 
THEIR DISCOVERY. 
A. fragariae Ritzema Bos, 1891. 
A. ormerodis R.B., 1891. A doubtful species, possibly the young of A. 
fragariae (Marcinowski, 1908). 
A. olesistus R.B., 1893. 
A. phyllophagus n. sp. 
